電気光学(EO)変調器


  • High Performance Lithium Niobate Amplitude & Phase Modulators
  • SMA RF Modulation Input Connector
  • Broadband DC Coupled or High Q Resonant

EO-PM-NR-C1

EO-AM-NR-C1

EO-GTH5M Application 

EO-PMT

EO-GTH5M

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ニオブ酸リチウム材料を用いた電気光学(EO)変調器

自由空間型電気光学(EO)強度/位相変調器は、当社の結晶成長技術と電気光学材料技術を組み合わせています。当社の電気光学(EO)変調器は、ハイパワー対応のために、ニオブ酸リチウムに酸化マグネシウム(MgO)が添加されています。変調器には、RF入力のSMAコネクタが付いており、当社の高電圧増幅器HVA200(下記参照)を直接接続することができます。当社では広帯域DC結合型と高Q共振型の2つのモデルをご用意しています。

Vpi Bias Voltage vs. Wavelength for EO Modulators
Click to Enlarge

EO変調器を駆動するのに必要な電圧(半波長電圧)は、光信号の波長に
依存します。「Amplitude Modulators(強度変調器)」と「Phase Modulators
(位相変調器)」の青と赤の線は、広帯域(非共振型)EO変調器の特性を
示しています。

特長

  • コンパクトなパッケージで高性能
  • 広帯域DC結合型、または高Q共振型
  • Ø2 mmの開口
  • MgO添加ニオブ酸リチウム結晶
  • SMA RF変調入力コネクタ
  • DC~100MHz
  • 製品組み込み用途(OEM用途)にも対応可能
*-C4バンド(400~600 nm)のAM変調器については、数Hz以上のAC変調でのみご使用ください。酸化マグネシウム(MgO)添加ニオブ酸リチウムはこの波長域の光に感度があるため、印加されたDC電圧が徐々に打ち消されます。光の強度が大きいほど、DC電圧が打ち消される速度が速くなります。従って、変調器を所定の動作点で動作させるためのバイアスとしてDC電圧をかけることはできません。

DC結合型広帯域変調器

当社の広帯域EO変調器は、RF性能を最大限に高めるように最適化された筐体に電気光学結晶が収納された構成です。RF駆動信号はSMA RF入力経由でEO結晶に直接接続されています。外部のRFドライバが、変調器に駆動電圧を供給します。結晶はDCから外部RFドライバの周波数リミット値まで変調可能です。増幅器の仕様要件については「仕様」タブをご参照ください。こちらの広帯域増幅器と位相変調器は、 -C4(400~600 nm)、-C1(600~900 nm)、-C2(900~1250 nm)、-C3(1250~1650 nm)のARコーティング付きでご提供しています。コーティングの反射率の詳細については「グラフ」タブをご覧ください。

高Q共振型変調器

共振型EO変調器は固定周波数で動作します。また、当社の製品には高いQ値の共振回路を使用しています。広帯域EO変調器の駆動に必要な電圧と比較すると、共振型EO変調器の動作電圧は大幅に低くなります。20 MHzで動作する当社の共振型の強度変調器および位相変調器は、標準品として、-C1 ARコーティング(600~900nm)でご用意しております。コーティングの反射率の詳細については「グラフ」タブをご覧ください。標準もしくはカスタム仕様のARコーティング、および0.1~100 MHzの共振周波数の指定も可能です。用途に応じた製品に関しては、当社までご相談ください。こちらの変調器の詳細については「仕様」タブをご参照ください。

ドライバとアクセサリ

当社の広帯域EO位相変調器は、駆動電圧が-Vπから+Vπに変動する時、 -180°から+180°の位相シフトを生成します。EO位相変調器では光信号の完全変調に±Vπの全電圧範囲が必要ですが、広帯域EO強度変調器では、駆動電圧が0から+Vπ 、または0から-Vπだけ変動させれば、光強度信号の完全変調できます。「EO変調器」タブでは図でご覧いただけます。

変調器の駆動には、標準的なファンクションジェネレータとともに、高電圧増幅器が必要です。 高電圧増幅器HVA200は、連続出力電流100 mAで±200 Vの出力、1 MHzの帯域幅、そして低ノイズが特長で、一定の動作条件において、当社の広帯域EO変調器の駆動に適しています。 一般的にHVA200で駆動するEO変調器は、必要な半波長電圧が≤200 Vのときに信号の完全変調が可能です。上のグラフのとおり、最大200 Vの電圧によりHVA200が完全変調可能な波長範囲は、EO強度変調器では約620 nmまで、非共振型のEO位相変調器では900 nmまでとなっています。しかし、増幅器の有効電圧範囲は「実験データ」に記載されている方法によって広げることができ、EO振幅変調器が最大1000 nmまで変調可能となります。

共振型または非共振型広帯域EO変調器の駆動について、さらに詳細な情報をご希望の場合は当社までお知らせください。

当社ではグラントムソン偏光子取付けアダプタのほか、当社のFiberBenchに取り付けるためのEO変調器用マウントもご用意しております(下記をご覧ください)。

変調器

Item #EO Amplitude Modulator
EO-AM-NR-Cx
EO Phase Modulator
EO-PM-NR-Cx
EO Resonant Modulator
EO-xM-R-C1
Modulator CrystalLithium Niobate (LiNbO3) Doped with MgO
Wavelength Range-C4400 to 600 nma400 to 600 nmN/Ab
-C1600 to 900 nm600 to 900 nm600 to 900 nm
-C2900 to 1250 nm900 to 1250 nmN/Ab
-C31250 to 1650 nm1250 to 1650 nmN/Ab
Clear Aperture2 mm Diameter2 mm Diameter2 mm Diameter
Input ConnectorSMA FemaleSMA FemaleSMA Female
Resonant Frequency RangeBroadbandBroadband20 MHzc
Half Wave Voltage, Vπ (Click for Plot)205 V at 633 nm (Typical)
(Click for Graph)
136 V at 633 nm (Typical)
(Click for Graph)
15 V at 633 nmd (Typical)
(Click for Graph)
Extinction Ratio>10 dBN/A>10 dB
Input Capacitance/Impedance14 pF14 pF50 Ohms
Max RF Input PowerN/AN/A3 W (35 Vpp)
Max Optical Power Density2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
  • -C4バンド(400~600 nm)で動作する変調はすべて、数Hz以上のAC変調でのみご使用ください。詳細については「概要」タブの緑枠内をご覧ください。
  • ご要望に応じて他の波長のARコーティングも可能。詳細は当社までお問い合わせください。
  • 共振周波数は0.1~100 MHzに対応可能。詳細は当社までお問い合わせください。
  • 大きな位相シフトを伴う変調や長波長での変調により、共振型変調器が3 WのRFパワー制限値(35 Vpp相当)を超えてしまう場合があります。

下記のグラフは、当社の4つの誘電体コーティングの標準的なコーティングロットでの反射率を示しています。網掛けの部分はコーティングの透過率の高いスペクトル範囲を示しています。

Electro-Optic Amplitude Modulator
Click to Enlarge

図2:EO強度変調器
Electro optic phase modulator
Click to Enlarge

図1:EO位相変調器
EO Phase Modulator Output vs. Bias Voltage
Click to Enlarge

図3:印加電圧(Vπの単位で表示)に対するEO位相変調器の出力。
曲線のX印は表中に記載された位相シフトです。
EO Amplitude Modulator Output as a Function of Bias Voltage
Click to Enlarge

図4:印加電圧(Vπの単位で表示)に対するEO強度変調器の出力。
曲線のX印は表中に記載されたEO強度変調器の状態における光出力(出力側偏光子透過後)です。

EO変調器概論

電気光学(EO)変調器は、変調器内を伝搬する電磁放射(光)の位相または強度(振幅)の変調用に設計されています。Qスイッチ、レーザのモードロック、光パルスの発生、側波帯(サイドバンド)の発生などの用途に使用されます。EO変調器は、ポッケルス効果を利用したデバイスです。ポッケルス効果は結晶に印加した電界強度(電圧)に比例して複屈折性が生じる1次の電気光学現象です。複屈折結晶では、結晶の光軸に対して平行に偏光する光の屈折率(n||)と、光軸に対して垂直に偏光する光の屈折率(n)が異なります。EO変調器で使用される結晶では、光軸は印加される電界方向に対して平行の方向です。

一般的に媒体の光学長さ(OPL)は、媒体を通る光の幾何学的距離に媒体の屈折率(nr)を乗じたものです。複屈折結晶の屈折率や光学長さは結晶の光軸に対する偏光によって決定されます。媒体の光学長さは媒体を通る光が蓄積する位相に直接関係します。ポッケルス効果が発現するとき、印加電圧を変調することにより、結晶内を伝搬する光が蓄積した位相の変調(位相シフト)が可能となります。長い結晶では位相シフトがより大きくなります。また、光学長さや蓄積された位相シフト量は、ともに光の波長によって変化します。EO変調器は印加する電圧信号によって生じる結晶の屈折率の変化を利用しています。

EO位相変調器

EO位相変調器は、光の偏光に影響を与えることなく電圧制御による変化する位相シフトを光に与えます。図1はその構成例の1つです。入射光は直線偏光で結晶の光軸にアライメントされています。前述したとおり、光軸(この図ではZ軸に対し平行)は印加する電界方向によって決まります。光が蓄積した位相は、光の波長、結晶の長さ(伝搬方向に対して平行のY軸に沿って測定)、そして光軸の屈折率n||によって変化します。n||の変動が光の位相変調を制御します。nの値は関係しません。図3では印加電圧(Vπの単位で表示)に対する位相シフト量とグラフがご覧いただけます。グラフのX印は表の値に相当します。Vπは半波長電圧と呼ばれ、piラジアンだけ出力位相をシフトさせる際に必要な電圧として定義されます。

EO強度変調器

EO強度変調器の例が図2でご覧いただけます。この構成では、入射光が結晶の光軸に対して45°の方向に直線偏光されています。光軸は印加する電界方向によって決まります。こちらの例の入射光は、振幅が同じで垂直な偏光成分、1つは光軸(Z軸)に沿って平行に偏光、1つは光軸(X軸)に沿って垂直に偏光の2つを合わせたものと同等だと説明できます。これらの2つの成分は結晶内を伝搬する際、異なる位相を蓄積し、結果、結晶の複屈折性を示します。光軸に対して平行に偏光される光の成分の光学長さは n||、垂直に偏光する光成分の光学長さはnにより求められます。印加電圧が変動するため、結晶の2つの屈折率の差も変動し、それにより2つの光成分の相対的な位相シフト量も変動します。

結晶の出射面における全電界の偏光(2つの成分を合わせたもの)は、2つの成分の位相差により変化します。結晶の出射面における光の偏光は2つの偏光成分が位相差が0°、もしくは180°のときは直線偏光、π/2ラジアンのときは円偏光、その他の時は楕円偏光になります。45°偏光子を通って透過する光の強度は、そこに入射する光の偏光によって異なります。印加電圧を変調すると、出射ビームの強度が変調されます。偏光子、つまりはEO強度変調器を透過する光は、直線偏光で、偏光軸に対し平行です。

図4の上の表は印加電圧の位相シフト量への影響と、結晶の出射面での偏光を示しています。グラフでは2Vπの変調範囲内の印加電圧により、偏光子を通って伝搬する光の振幅を示しています。(曲線のX印はグラフ上の表の値に相当します。) 図2で示している構成については、入射光の振幅を完全変調するためには電圧信号が0 VからVπ(もしくは-Vπから0 V)に変動しなければなりません。最大値と最小値の両方を得たい場合には、変調器は0 Vを通って+Vπまたは-Vπのどちらかに達しなければなりません。セットアップに1/4波長板を追加すると必要電圧の絶対値を小さくすることができます(「実験データ」タブをご覧ください)。

EO変調器の駆動

EO変調器は図1、図2のように電圧を光の伝搬方向に対して垂直に印加したり、平行に印加するよう構成可能です。電圧を横方向に印加する利点は、図を見てわかるように、光が電極を通る必要がなくなることです。これにより、一般的には変調器内の透過率が向上し、動作波長に対して不透明な電子材料が使用できるようになります。さらにこの横方向の構成では、光学長さが電界と結晶の長さを乗じた値に比例します。

高電圧の可変電源、例えばファンクションジェネレータと高電圧増幅器の組み合わせにより数百ボルトの電圧供給を可能とする電源構成が、通常自由空間型のEO変調器の駆動に使用されます。「概要」タブ内のグラフで示したように、EO変調器の駆動に必要な電圧は、変調する光の波長が長くなるにつれ、増加します。このため、長波長の光信号を完全変調するために必要な電圧は、その高電圧電源の出力範囲を上回る場合があります。例えば、高電圧増幅器HVA200の出力範囲は±200 Vで、光の波長が610 nm未満の広帯域EO変調器EO-AM-NRや、波長が900 nm未満のEO-PM-NRの駆動に適しています。より長い波長だと、この増幅器では光信号の完全変調に必要な電圧を供給することができません。しかしEO-AM-NRのようなEO強度変調器にHVA200を使用する場合、変調器の入射部の前に1/4波長板を置くことで、使用可能な電圧範囲を広げることができます。手順についての詳細は「実験データ」タブでご覧ください。

ファイバ出力型EO変調器(LN変調器)に必要な駆動電圧は大抵、自由空間型EO変調器よりも著しく低くなります。多くの場合、これらの変調器の半波長電圧は約4 Vで、用途のニーズに合わせた変調周波数を生成可能な高速電圧ドライバを適用することが重要です。ファイバ出力型のEO位相変調器を1 GHzまで駆動することに成功したファンクションジェネレータと増幅器を使用した基本的な構成例がこちらでご覧いただけます。

Electro-optic amplitude modulator no QWP
Click to Enlarge

図1:EO強度変調器
(1/4波長板の設置なし)
Electro-optic amplitude modulator with QWP
Click to Enlarge

図2:EO強度変調器
(入射側に1/4波長板を設置)

EO強度変調器と1/4波長板を組み合わせて必要な駆動電圧を下げる方法

高電圧の可変電源、例えばファンクションジェネレータと高電圧増幅器の組み合わせにより数百ボルトの電圧供給を可能とする電源構成が、通常自由空間型のEO変調器の駆動に使用されます。「概要」タブ内のグラフで示したように、EO変調器の駆動に必要な電圧は、変調する光の波長が長くなるにつれ、増加します。このため、長波長の光信号を全振幅または位相範囲で変調するために必要な電圧は、その高電圧電源の出力範囲を上回る場合があります。詳細については「EO変調器」タブをご覧ください。

Lab Facts Complete Summary

EO-AM-NRのようなEO強度変調器の場合、変調器の入射部に1/4波長板を置くことにより完全変調するのに必要な最大電圧を下げることができます。高電圧電源が起因で完全変調ができない場合、1/4波長板の使用によりEO振幅変調器の変調がより深くなります。図1と図2では1/4波長板が設置されていないEO強度変調器と、設置されているEO強度変調器がご覧いただけます。実験で使用されているのは出力電圧範囲が±200 Vの高電圧増幅器HVA200で、電気光学強度変調器EO-AM-NR-C1により前述のアプローチを示しています。こちらのタブには実験のまとめが記載されています。詳細については赤い「Lab Facts」ボタンをクリックしてください。

実験では光源としてHeNeレーザHRS015(633 nm、旧製品)とピグテール付きレーザLP980-SF15(980 nm)を使用しました。光源の直後の直線偏光子(LPVISB100またはLPNIR100)は、入射偏光がEO強度変調器EO-AM-NR-C1の光軸に対して45°になるよう配置しました。変調器の出力部に配置されたもう1つの直線偏光子は最初の直線偏光に平行にアライメントされました。ファンクションジェネレータが出力する100 kHzの三角波を増幅するために使用されたHVA200は、EO強度変調器を駆動するため様々な電圧信号(最大±200 V)を生成しました。EO強度変調器を透過する光が正弦波状に変調されるよう、変調器の駆動には三角波を選びました。データはEO振幅変調器の前に1/4波長板(WPMQ05M-633またはWPMQ05M-980)を配置した構成と配置しなかった構成で取得しました。1/4波長板使用時には、波長板の軸が結晶の光軸に対して平行となるよう配置しました(図2で変調器に対する1/4波長板の位置と方向がご覧いただけます)。

EO amplitude modulator output vs. bias voltage
Click to Enlarge

図3:印加電圧に対するEO強度変調器の出力。図1のように1/4波長板が含まれていないセットアップの場合。曲線のX印はグラフ上の表の状況を示す位置です。

EO変調器」タブや図3で説明している通り、1/4波長板がEO強度変調器の前に配置されない場合(図1)、変調器に入射される光は直線偏光で、入射光の強度を完全に変調するためには、印加電圧信号を0 VからVπ(または -Vπから0 V)に変動させなければなりません。EO-AM-NR-Cを使用し、一般的な過変調方法(Vπよりも大きなPeak-to-Peak電圧を適用)により、波長633 nmでのVπを測定しました。Vπの測定値は633 nmで220 Vで、Vπは波長が長くなるにつれ、直線的に増加します。HVA200の電圧出力が(最大の)±200 Vに達すると、この波長での出力信号を完全に変調する電圧を供給できなくなります。増幅器の出力電圧を飽和させて変調器を駆動しようとすると、図4のとおり、変調信号の振幅は歪んでしまいます。

1/4波長板をEO強度変調器の前に配置した場合、EO強度変調器に入射した光は円偏光になります(図2参照)。基本的に1/4波長板が変調器の入射光に光バイアスをかけるのです。このバイアスにより、入射光の完全変調に必要な電圧が、0 Vから+Vπもしくは-Vπではなくなり、-1/2 Vπ~1/2 Vπとなります。図5の表では、様々な駆動電圧でのEO結晶の出射偏光を示しています。またグラフは駆動電圧に対する偏光子透過後の振幅を示しています。1/4波長板を使用した場合(光源の波長は633 nm)、EO強度変調器の完全変調に必要な駆動電圧範囲は±110 Vです。これは十分にHVA200の範囲内です。この方法により生成された完全変調信号は図6で示されています。

1/4波長を光学セットアップに組み込むことで、増幅器の使用可能な動作範囲は効果的に倍増します。1/4波長板を作るバイアスにより、HVA200がEO-AM-NR-C1の全動作波長範囲を駆動できるようになります。この方法によりHVA200が1000 nm波長までのEO-AM-NR-C2の完全変調も可能にします。増幅器は最大電圧出力値が大きくなると値段も上昇するのでこの方法を用いることにより節約につながる場合もあります。この実験に使用された装置や実験結果の詳細は こちらをクリックしてご覧ください。

EO Modulator Response with Saturated Amplifier
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図4: グラフでは、信号の完全変調に必要な Vπが増幅器の供給可能な最大駆動電圧を上回る場合において、増幅器を飽和させて完全変調を試みる際に起こる変調の歪みを示しています。この信号の波長は633 nmです。
QWP shifts modulator response vs bias voltage
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図5: 図2のようにEO振幅変調器の前に1/4波長板を挿入すると、出力振幅と印加電圧の関係性が変化します。0 Vのバイアス電圧では、出力振幅がMinとMaxの中間地点にあります。曲線のX印はグラフ上の表の状況を示す位置です。
Full response of EO modulator when QWP used
Click to Enlarge

図6: グラフでは図2のような光学セットアップに1/4波長板を挿入することで、歪みのない、完全変調された633 nm信号が実現しています。

Posted Comments:
Jeremie Margueritat  (posted 2024-03-27 21:51:42.913)
I envisage to purchase teh EO-AM-NR-C4. However I read that in this range the AM modulators operating in the -C4 band (400 - 600 nm) should only be used for AC modulation above a few Hz. I would like to work up to 500kHz in Amplitude modulation with 515 nm laser. Is the EO-AM-NR-C4 adapted for this use? Best regards
Seungeun Oh  (posted 2024-01-24 23:50:08.753)
Which direction relative to the housing is the fast axis of the crystal in Resonant EO Modulators?
Alexia RAVAILLE  (posted 2024-01-09 07:57:29.123)
Dear Tech support team, My question might seem stupid but I have a non resonant PM EO-PM-NR-C1 and I would like to know its input impedance. In the datasheet, it's specified that the resonant has 50 ohms of input impedance and the non resonant have 14pF capacitance but I can't find the info about the impedance of the non resonant. Does it mean that it's only capacitance with no impedance when non resonant ? Also, how do we know if we have a resonant or a non resonant PM if we've lost the packaging of the component ? Thank you and happy new year.
ksosnowski  (posted 2024-01-10 02:47:40.0)
Hello Alexia, thanks for reaching out to us. If the EOM is non-resonant, then you will be able to modulate the phase from DC to 100 MHz or so, as long as your driver can support it. If resonant, then modulation will only be possible near the resonance frequency (20MHz for our standard model). As long as you operate safely below the RF input maximum (3 W, 35 Vpp), you will not damage the resonant modulator. On resonance, the EOM will have a nearly 50 Ω impedance, whereas far from resonance it will have a highly reactive impedance, and will burn out if the 50 Ω resistance dissipates too much RF power. Since the non-resonant EOMs have a ~14 pF impedance (purely reactive aside from small parasitics) they do not dissipate power. This is why we don't spec a Maximum RF Input Power for the non-resonant modulators.
Sebastian Eppelt  (posted 2023-10-05 10:17:12.85)
Hello, we were planning to use a EO-PM-NR_C4 in our setup to surpress phase noise of one of our lasers. We have seen with home-built free-space EOMs that these can exhibit quite strong mechanical noise around ~1 MHz. Are there noise characteristics for the this model?
Guangying Ma  (posted 2023-08-16 12:47:50.81)
Hello, I have bought the EO-PM-NR-C4. I am using a 488 nm (20 mW) laser as the input. Then I calculated the Vpi is 152.0 V. I applied a AC power, with -152 and 152 V, 1000 Hz square wave as the driving voltage. I found that the polarization of the input light was changed, however, the changed angle is very small, which is smaller than 15 degree. Could you help me to find what is the problem? Is the driving voltage I used is correct? Thanks.
ksosnowski  (posted 2023-08-29 05:48:04.0)
Hello Guangying, thanks for contacting us. This is the correct Vpi however if the driver is not suitable it could struggle to switch the voltage fast enough resulting in effective peak voltage attenuation or if the input polarization alignment is incorrect this can result in a lack of dynamic range with the EO modulator. Our HVA200 driver is suitable for this application based on the amplitude, waveform, and total bandwidth. In case your laser system is unable to be rotated to change the input polarization, a halfwave plate can be used to effectively bias the input polarization angle before entering the EOM. I have reached out directly to discuss your application in further detail.
Jihoon Kang  (posted 2023-04-21 11:47:07.397)
Can you tell me the "maximum laser durability" (ex: 2.5 MW ...) of the modulator? I also want to know about the "wavelength coverage".
cdolbashian  (posted 2023-04-26 09:29:57.0)
Thank you for contacting us Jihoon. All of this information (and more) is available above in the "Specs" tab. Additionally I would read through the document in the "Lab facts" tab as we have documented some testing with these devices.
Cristian Tong  (posted 2023-01-01 02:37:58.223)
Hello, I would like yo ask you about the insertion loss of the free space electro optic phase modulator EO-PM-NR-C1. This parameter is not specified in the specs of the device. Thank you
cdolbashian  (posted 2023-01-10 02:36:19.0)
Thank you for contacting us Cris! If you are referring to the transmission vs reflection, we would expect ~.2% reflection over the AR coating range, and >98% transmission through the crystal (again, while operating within the AR coating range). I have reached out to you directly to discuss this inquiry.
stefano chiodini  (posted 2022-09-09 10:20:53.787)
Good morning, I have the following question. For my project I need to use the C4-C1-C2-C3 EOM-AM of Thorlabs to cover a range from 400 nm to 1600 nm. The Vpi required voltages go from about 100 V to 600 V following your graph. Since we could have troubles in covering the 300 V-600 V I was wondering if a phase EOM could be used... They have indeed lower Vpi voltages but I do not really understand the difference with the AM-EOM. Could you please help me out in this? Following your phase EOM description: "the value of n⊥ is not a factor". What does it mean? that only the parallel beam goes through? Thank you, Stefano
Michael Lim  (posted 2022-07-19 11:40:28.22)
Can this phase modulator be adapted for use at 2000nm?
jgreschler  (posted 2022-07-22 04:21:26.0)
Thank you for reaching out to Thorlabs. We do have custom wavelength capabilities for our EOM product line, you can request a quote by emailing techsupport@thorlabs.com. I have reached out to you directly with more information.
Farooq Khaleel  (posted 2021-10-04 18:12:37.967)
Dear Sir/Madam, I hope that this message finds you well. Please could you inform me about if these EO modulators supports bidirectional modulation? I mean could I apply the incident laser from the output port and extract the output from the input port? and vice versa? In addition, what is the minimum detectable input power in Watt? Thank you very much. Yours sincerely,
YLohia  (posted 2021-10-07 08:20:17.0)
Hello, thank you for contacting Thorlabs. Yes, the modulators are bidirectional. These non-resonant modulators are a purely capacitive load- the power does not dissipate in the crystal. We do not specify an upper limit for how much power can be sent through the modulator. In these cases the driver is typically the limit on power, not the modulator. For our resonant modulators, e.g. EO-PM-R-20-1, the max RF power that can be sent through the device is 3W. If you are inquiring about the minimum optical input power, the modulators have no minimum input power (this is true for both the resonant and non-resonant models). The light is attenuated by a fixed amount depending on the applied voltage and the wavelength of the light. Think of it as a variable attenuating filter; it will absorb some percentage of the light regardless of how little power is put through it. The modulator is not the limit on how little power can be used in a system; it depends on how sensitive the detector is.
T I  (posted 2021-09-24 12:11:21.52)
Dear Thorlabs support team, I am using your free space LN modulators and need to know the exact crystal lengths. We could find some info in your previous replies to feedback comments, but it seems there is a conflict between the two responses below. YLohia (posted 2019-11-12 11:18:13.0) Our PM use only one LN crystal of 20mm length, as opposed to two orthogonal 20mm (adding up to 40mm) crystals used for AM nbayconich (posted 2017-05-03 10:04:19.0) The crystal length of our free space Amplitude modulators is 20mm. The LiNbO3 crystals in our free space phase modulators are 40mm in length. Could you tell us the exact crystal lengths of the amplitude and phase modulators?
YLohia  (posted 2021-10-08 03:03:04.0)
Hello, thank you for your feedback. I seemed to have made a typo on my response posted on 2019-11-12 11:18:13.0 (which I have now corrected). The phase modulators only use one crystal of 40 mm length. The amplitude modulators use two orthogonal crystals, each 20 mm long, adding up to a total of 40 mm length. My sincere apologies for any confusion caused by the previous post.
dongxu Bai  (posted 2021-06-01 16:45:52.517)
调制信号的频率范围是什么 What is the frequency range of the modulated signal
YLohia  (posted 2021-06-04 02:48:43.0)
These modulators can be used from DC to 100 MHz.
user  (posted 2021-05-24 18:52:46.0)
Hi, could you tell me the price of the customized resonant EOM? Thanks.
YLohia  (posted 2021-05-27 02:39:22.0)
Hello, custom items are quoted by emailing your local Thorlabs Tech Support team (in your case, techsupport.uk@thorlabs.com). We will discuss the pricing directly.
Michal Pawlak  (posted 2020-10-24 02:46:00.01)
Dear Sir Madam could you please explain my problem.When I will buy your EO amplitude modulator with driver I can modulate between DC 100 MHz. Or frequency is limit to 1 MHz as is stated in description of driver. best wishes Michal
YLohia  (posted 2020-10-26 09:34:30.0)
Hello Michal, thank you for contacting Thorlabs. The EOM itself is capable of modulating up to 100 MHz but the HVA200 limits that capability to 1 MHz.
Haechan An  (posted 2020-10-18 18:53:46.15)
Hi, I want to create sidebands at 780 nm using EO-PM-NR-C1 with a modulation frequency of around 20 MHz. But it turned out that we need high voltage to see those sidebands easily. (Probably need a voltage higher than 50 V but we only can go up to 10 V right now.) Can you tell me the equivalent electric circuit of EOM so I can build a resonant RLC circuit using resonators and inductors? Or is it enough to assume the EOM as a 14 pF capacitor?
YLohia  (posted 2020-10-23 03:34:35.0)
Hello, thank you for contacting Thorlabs. The modulator can be modelled purely as a 14pF capacitor. The exact capacitance is given on the serialized test sheet that ships with each unit.
user  (posted 2020-10-19 16:59:00.947)
我想要用这个电光调制器实现633nm激光的偏振调制,请问能够实现吗?请问电光调制器配置有偏振片吗?
YLohia  (posted 2020-10-19 03:12:46.0)
An applications engineer from our team in China (techsupport-cn@thorlabs.com) will reach out to you directly.
宝利 刘  (posted 2020-06-15 08:20:11.92)
我想利用这个EOM调制f=76MHz脉冲激光,调制频率为f/4,即2个脉冲透过,2个脉冲不透过。这个调制频率f/4由激光器的频率锁定。这种可以定制吗?
YLohia  (posted 2020-06-15 09:53:28.0)
Thank you for contacting Thorlabs. An Applications Engineer from our Tech Support team in China will reach out to you directly.
Caroline Muellenbroich  (posted 2019-11-12 09:43:11.917)
Hi Thorlabs team, I am trying to modulate the power of a pulsed 1300nm laser with a EO-PM-NR-C3 using a voltage amplifier that has an output of +/- 150V. The half wave voltage for my wavelength is 300V which I cannot supply. Am I right in thinking that by supplying 150V, and using a quarter waveplate before the input, that is inputting ciruclarly polarised light into the EOM, I should be able, with a Glan Thompson at the output of the EOM, to modulate the output power of my laser? Many thanks.
YLohia  (posted 2019-11-12 11:18:13.0)
Hello Caroline, thank you for contacting Thorlabs. Your understanding is correct regarding the use of the waveplate. By using a quarter waveplate on the input, you can cut down the V_pi in half. We have more information regarding this technique in the "Lab Facts" tab of this page. That being said, we do not recommend attempting amplitude modulation with a phase modulator. While PMs can be used as AMs with additional polarization optics, they will not make good amplitude modulators. Our PM use only one LN crystal of 40mm length, as opposed to two orthogonal 20mm (adding up to 40mm) crystals used for AM, that eliminates static birefringence. These crystals exhibit thermal birefringence, which means that a phase modulator will have thermal drift issues when used as an amplitude modulator. One good question would be why phase modulators exist since amplitude modulators would do exactly the same thing while offering better performance due to the lack of thermal issues. The reason is that thermal effects are relatively insignificant for PM due to the input beam being polarized along one of the crystal axes. This thermal drift produces a DC phase shift (equivalent to adding few um of OPL). Our phase modulators are made with MgO-doped lithium niobate crystals. This material works well for phase modulation, and the MgO doping helps to increase the material's resistance to photorefractive damage. However, one drawback to this material is that it exhibits increased wavefront distortion (as opposed to undoped lithium niobate). For most phase modulation applications, wavefront distortion of the optical beam does not present any problems (can cause problems when being used for interferometry resulting in poor phase contrast), but when used as an amplitude modulator, the wavefront distortion causes poor extinction ratios.
kar-hooi_kuan  (posted 2019-02-20 06:15:13.65)
Hi, I'm interested in Amplitude Modulations EO Modulators. I would like check with you if the optical input can be connectorized with FC/APC connectors? I will need it to be connectorized. If it can be connectorized, could you please quote me together with the EO MOdulator High Voltage driver? By the way, what is the maximum modulation frequency supported by this EO-PM-NR-C3? Thanks a lot.
YLohia  (posted 2019-02-21 08:48:45.0)
Hello, thank you for contacting Thorlabs. Unfortunately, this cannot be connectorized as it requires a collimated free space beam in order to work properly. What wavelength are you hoping to use this for? If it's around the 1550nm range, I would recommend looking into our fiber coupled LN modulators here : https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3918. These can go up to 10 GHz, whereas the model you were interested in is suitable up to only 100 MHz. Another option would be using a FiberBench of at least 70mm length with two Fiberports to make the free space EOMs fiber-compatible. Please see the bottom of this page for more information.
zenin  (posted 2019-02-20 10:42:19.48)
Hi, I am investigating the project of building fast noise eater (faster than 1 MHz) for my free-space lasers by using your EO modulators. I am wondering, can you make EO modulator witohut anti-reflection coating? It is because I have several sources from in VIS and NIR ranges (600-1800 nm). Also I am wondering, can Thorlabs make such noise eater, and if yes, how much will it cost? Looking forward to your reply. Best, Vladimir
YLohia  (posted 2019-02-21 09:02:09.0)
Hello Vladimir, thank you for contacting Thorlabs. Quotes for custom modulators can be requesting by emailing your local Thorlabs Tech Support group (techsupport.se@thorlabs.com in your case). We will reach out to you directly to discuss the possibility of offering uncoated crystals. That being said, please note that the total transmission will suffer greatly when using uncoated crystals. The amplitude modulators consist of two lithium niobate crystals, which means that the reflectivity will be quite high from a total of four surfaces since the optical index is about 2.3. When this happens, you can get multiple reflections within the crystal that see different amounts of modulation and can interfere with each other. The workaround for this would be to tilt the crystal as far as possible and then prevent the reflected beams from getting in the system by clipping them with an aperture or edge of some kind. Unfortunately, we are unable to offer a fully designed 1 MHz noise eater at the moment, though it is something that I will suggest on our internal engineering forum.
vinx-d  (posted 2019-01-17 04:35:15.51)
I am going to use the HVA200 in order to amplify a input voltage. I was wondering if I can amplify the bias without using any input.
YLohia  (posted 2019-04-01 04:43:39.0)
Hello, thank you for contacting Thorlabs. I reached out to you at the time of the original post in order to gather more information about your request. Please send us an email at techsupport@thorlabs.com if you did not receive our email.
kkss0330  (posted 2018-10-11 00:29:20.047)
Hello, I bought EOM that model number of EO-AM-NR-C4, I will operate laser source wavelength 633nm. I know that this supports a wavelength band from 400 to 600nm, can EOM work well from 633nm?
YLohia  (posted 2018-10-11 09:53:27.0)
Hello, thank you for contacting Thorlabs. The -C4 coating typically has a reflectivity of around 0.5-0.7% at 633nm. Since you already have the EOM with you, we recommend that you test it out yourself to see if the change in performance fits your requirements.
baudin  (posted 2018-03-27 16:27:15.35)
Hello, the specs say the load impedance is 14 pF, can you provide the loss angle function of frequency?
YLohia  (posted 2018-04-03 10:26:35.0)
Response from Yashasvi at Thorlabs USA: Hello, thank you for contacting Thorlabs. While we don't have a loss angle as a function of frequency spec at the moment, we do have a spec for the loss tangent @ 400 °C: x-axis: tan(δ) = 0.0006 y-axis: tan(δ) = 0.001 We have seen values around ~0.003 for the loss tangent at 1 GHz. This is a property of the material (lithium niobate) itself.
parksj003  (posted 2018-01-28 22:03:42.99)
I am going to use a HVA200 with EO-AM-NR-C1 for fast light intesnity modulation (on/off). I am wondering the rise/falling time of HVA200 and the time dealy between input and output.
nbayconich  (posted 2018-02-23 10:49:58.0)
Thank you for contacting Thorlabs. The typical rise/fall time of the HVA200 alone is about 350ns at 1Mhz, however the HVA200 is typically limited to the slew rate which is 400V/µs. We have not yet tested time delay when using an intensity EO modulator with the HVA200 at the moment.
tanmaybhwmk3  (posted 2017-11-15 01:51:46.267)
Hi. What is the expected insertion loss of the EO-AM?
tfrisch  (posted 2017-11-20 05:18:05.0)
Hello, thank you for contacting Thorlabs. The loss through the modulator is <1dB, typically about 0.5dB.
fyk15isy  (posted 2017-10-02 15:09:40.037)
Hi! I am looking for an EOM to do an amplitude modulation of 880 nm beam from OPO with an average power of 1 W. (It actually produces 5 ps pulses with 80 MHz repetition rate). I plan to focus the beam into the EOM since my beam diameter is too large for this EOM. Will this EOM be able to withstand this power when using short focal length lenses (50 - 100 mm lenses)?
tfrisch  (posted 2017-11-14 02:48:07.0)
Hello, thank you for contacting Thorlabs. These EOMs are intended to be used with a collimated input. If there is significant convergence or divergence, this would give an angular dependence on the optical path length which would affect the retardance and therefore amplitude modulation. I will reach out to you directly about damage and other methods of limiting the beam diameter.
user  (posted 2017-05-02 11:05:15.013)
What's the LiNbO3 crystal length of EO-AM-NR-C1? 20 mm?
nbayconich  (posted 2017-05-03 10:04:19.0)
Thank you for contacting Thorlabs. The crystal length of our free space Amplitude modulators is 20mm. The LiNbO3 crystals in our free space phase modulators are 40mm in length. A tech support representative will contact you directly.
melanie.lebental  (posted 2017-02-06 09:19:47.293)
Hello, Please, what is the maximal speed of modulation from 0 to Vpi for the wavelength 532 nm ? 100 kHz ? 1 MHz ? Best regards,
tfrisch  (posted 2017-02-14 02:10:19.0)
Hello, thank you for contacting Thorlabs. The maximum frequency will depend on the max current that can be supplied by the voltage driver, and the function of that signal. In the case of a sine wave, the maximum frequency is Imax/(pi*Vpp*C) where Imax is the max current of the driver, Vpp is the peak to peak voltage of the signal, and C is the capacitance of a non-resonant modulator (14pF for our units). I have contacted you with information on this derivation.
parksj003  (posted 2016-12-01 16:27:36.453)
Hello, I am looking for fast polarization modulator. The sorce we are using is femto-seond laser (wavelength ranging from 700-1000 nm, Power ~3W, beam diameter ~1.5mm). I think EO-AM-NR-C1 might be fine, as it can fastly alternate the laser beam polarization (but I am not sure yet). We need to alternate the beam polarization either vertically or horizontally (with a speed of at least 5 kHz). Would you let me know if there is proper solution for us? Best, Seongjun
tfrisch  (posted 2016-12-01 08:41:41.0)
Hello, thank you for contacting Thorlabs. I'd like to ask a few questions about your laser, so I will contact you directly about that. As for changing the polarization state, in general, that is how these freespace amplitude modulators work, you would just not use an output polarizer to drop the intensity for the state crossed to the input state. If your input is vertical, then a voltage of Vpi would give horizonatally polarized light. The fast axis of the crystal is at 45 degrees with respect to the housing, so you may use horizontal or vertical input.
gksthf666  (posted 2016-11-22 05:18:04.04)
To whom it may concern, Hi, I'm Hansol Jang and I need some resonant type amplitude modulator with following properties. 1. Resonant frequency : 80 MHz 2. AR coating : 600 - 900 nm (actually, I need 750 to 1000 nm range) 3. Polarization : Schematic diagrams shown in website are pretty confused.. Which one is correct? (single crystal with linear polarizer or dual crystals) It is suitable for my system that input and output polarization is vertically or horizontally changed with respect to base (bottom) of EOM module. Best, Hansol Jang
tfrisch  (posted 2016-11-22 07:32:36.0)
Hello, thank you for contacting Thorlabs. For your first two notes, we can provide a quote for you. As for the polarization, the free space amplitude modulators use two LiNbO3 crystals which have their fast axes offset to mitigate changes in birefringence due to thermal effects. These are mounted at +45 degrees and -45 degrees with respect to the housing, so for the best extinction, the input polarization state should be vertical or horizontal. The EOM introduces an ellipticity to the polarization state, so an output polarizer will cause the change of amplitude. This output polarizer can be either parallel to or crossed to the input polarization (horizontal or vertical).
jchg2758  (posted 2016-08-29 12:33:53.187)
Hello, Recently I used the eo phase modulator for generating 2 MHz sidebands on 80 MHz rep. rate frequency comb. A RF signal generator makes 20 dBm 2 MHz signal and your company's 200 V amplifier makes additional bias and amplification. However there is only -70~-80 dBm sidebands and it hard to find the decreasing of fundamental. I set the vertical pol. input and enough optical power. Is there any mistake about choosing product? align miss? lack of amplification? I'm look forward to your answer. Thanks.
tfrisch  (posted 2016-09-01 11:47:51.0)
Hello, thank you for contacting Thorlabs. The relative intensity of sidebands will be dependent on the modulation depth of the phase. The relation between voltage depth and phase modulation depth is wavelength dependent. I will contact you directly about your application.
killian  (posted 2016-08-03 11:14:04.56)
Hello, I am looking for an EOM to use as a phase modulator for both 532 nm and 1064 nm light. The beams are CW, co-propagating. I would need an AR coating that covers both wavelengths because I don't want much loss passing through the EOM. Can you provide a specialty coating? The biggest requirement though is the variation in the half-wave voltage with wavelength. I need a controllable, differential phase shift of the 532 and 1064 nm light. In other words, I need a material for which the half-wave voltage deviates as much as possible from being linear with wavelength. I want to be able apply a voltage and shift the 1064 one wavelength while shifting the 532, for example, 2.5 wavelengths instead of two. It doesn't have to be exactly that, but I need the differential control of the relative phases. The provided curves for Lithium Niobate look promising. If I can apply up to about 1000V, I can shift the 1064 phase 2 wavelengths, while shifting the 532 4.5 wavelengths, which would be just enough for my application. What is the peak DC voltage that can be applied to your phase modulators? Thanks, Tom
gkatsop  (posted 2016-02-05 18:27:12.06)
Hi. We are interested in modulating the polarization of a 1315nm laser (from right-circular to left-circular polarization and back) at a frequency of a few kHz, using your EO-AM-NR-C3. However we notice that your HVA200 amplifier provides a +/-200V output, whereas the half-wave voltage at 1315nm is around 450V. Supposedly then, the HVA200 is of no use for us and we would have to search for another amplifier, correct? Is there something you could propose in this direction? Is this EOM otherwise ok with our application? Kind regards, George.
besembeson  (posted 2016-02-10 12:47:22.0)
Response from Bweh at Thorlabs USA: With a suitable driver and a quarter waveplate in a rotation mount at the input, and a linear polarizer and quarter waveplate at the output, you should be able to achieve this. We will contact you with suggestions for high voltage amplifiers.
peh  (posted 2015-10-22 17:53:25.073)
Is it possible to use a modulation signal with the following properties together with the HVA200 and E=-AM-NR-C4? repetition period 100 µs High signal time 1 µs
besembeson  (posted 2015-10-28 11:16:54.0)
Response from Bweh at Thorlabs USA: The slew rate for the HVA200 is 400V/us. If you require up to V_pi, for the EO-AM-NR-C4, you will need about 200V maximum (at 600nm for example), which will take about 0.5us at best from the HVA200 so you will end up with an almost triangular waveform, instead of a 1us/100us square wave. The shape of the waveform will vary depending on your wavelength and voltage requirement. If the 1us (High signal) excludes the voltage ramp up time, then this could be suitable.
cweidner0  (posted 2015-02-10 11:35:56.063)
Is this EOM suitable for use in interferometric applications? Is there significant wavefront distortion as the laser passes through the crystal? Has this distortion been quantified in any way?
besembeson  (posted 2015-02-12 12:05:11.0)
Response from Bweh at Thorlabs USA: We don't have data yet quantifying the transmitted wavefront error for these devices. I will followup by email to discuss your application further.
user  (posted 2014-10-29 12:56:55.817)
Wondered if HVA200 includes a BNC cable? It would be better for us to know on a webpage if there is chart telling us what are included.
jlow  (posted 2014-10-30 01:46:14.0)
Response from Jeremy at Thorlabs: Thank you very much for your feedback. The HVA200 includes a BNC to SMA cable. We will look into adding this on the website.
aklossek  (posted 2014-10-22 14:09:33.31)
Dear ladies and gentlemen, please tell me the total geometrical length of the lithiumniobat crystals within the EO-AM-R-20. I need this to compensate the delay caused by this optic. Best regards André Klossek
jlow  (posted 2014-10-22 01:53:19.0)
Response from Jeremy at Thorlabs: The amplitude modulator has two crystals and each one is 20mm long.
aklossek  (posted 2014-10-16 10:16:47.867)
Dear ladies and gentlemen, I am interested in your EO-AM-R-20-C1. My question is about the temperature stability. Does the EOM need some specified, stable climate conditions (temperature)? Best regards André Klossek
jlow  (posted 2014-10-22 03:57:46.0)
Response from Jeremy at Thorlabs: The amplitude modulators are made with 2 crystals oriented 90° from each other. This configuration greatly reduces the temperature sensitivity so you can use this in a regular lab environment. I will contact you directly to discuss about this further.
h.schultheiss  (posted 2013-10-17 16:12:25.66)
Hello, I plan on using one of your modulators for the generation of sidebands with a frequency separation from 1 GHz to 20 GHz. I used already your phase modulator for this purposes and it works for a couple of frequencies, but now want to build a new setup and I was wondering, if I could use the amplitude modulator as well. What is actually the difference between the amplitude and the phase modulator, the price is the same. Best wishes, Helmut Schultheiß
jlow  (posted 2013-10-17 16:29:00.0)
Response from Jeremy at Thorlabs: The phase modulator is made with one long crystal whereas the amplitude modulator is made with two crystals, oriented at 90° to each other, and oriented 45° relative to the horizontal (see the picture on the amplitude modulator subgroup). With a horizontally or vertically polarized beam, the amplitude modulator is actually acting more as a variable wave plate and it requires a linear polarizer on the output to make it an actual amplitude modulator. In theory you could use the amplitude modulator to generate sidebands but this can be done much better with the phase modulator. We will contact you directly to discuss about this further.
ahmmadvand  (posted 2013-08-09 14:14:19.96)
Is it possible to produce circular polarization by using an electro optic modulator? What are the advantages/disadvantages in comparison to photo-elastic modulator (PEM). I would like to know the best way for producing circular polarization by using thorlabs products.
cdaly  (posted 2013-08-15 16:16:00.0)
Response from Chris at Thorlabs: Thank you for using our feedback tool. Using a phase modulator is going to involve a relatively complex setup to create polarization. If you are looking to create a circularly polarized free space beam, I would recommend using a 1/4 wave plate for a linearly polarized source. If your source is randomly polarized, I would say t just pass it through a polarizer initially, then through the quarter waveplate.
jpott  (posted 2013-05-17 08:56:50.653)
I have a questin to your broad-band phase modulators: what is the broadband phase behaviour: will a given voltage result in the SAME phase over all frequencies within the passband, or does the phase-modulator introduce voltage-dependent dispersion? thanks - j-uwe pott
tcohen  (posted 2013-05-23 13:39:00.0)
Response from Tim at Thorlabs: The voltage to get a given phase is a function of wavelength. You can see the half-wave voltage vs. wavelength in the manual on page 4. I will contact you to discuss this further.
proto.vladimir  (posted 2013-05-02 18:35:23.707)
1). AOM: in the figure with two crystals in series: is it true that the voltages are applied in the same polarity with respect to optical axis direction? 2). POM: what is the phase change at half-wave voltage Ul/2? 3). POM-AOM: why Ul/2 is 2 times bigger for AOM relative to POM?
cdaly  (posted 2013-06-12 16:03:00.0)
Response from Chris at Thorlabs: Thank you for using our feedback tool. The image on the web indicating the orientation for the crystal axis and voltages as of 6/12/13 is incorrect in this regard and we will have this updated just as quickly as possible. Thank you for pointing it out. The nominal Vpi of PM is 2/3 of the Vpi of AM as the curve shows is due to the polarization direction of the light relative to the crystal axis. For AM modulations, the light is polarized 45 degree to the axis, and both crystal pieces contribute to phase shift equally. The phase shift in this case is mainly decided by the difference of the EO coefficients (r33-r11). For PM modulation, the light is supposed to be polarized along the Z axis to maximize the EO effect, therefore its phase shift is decided by r33 only.
sharrell  (posted 2013-06-14 15:02:00.0)
Additional Response from Sean at Thorlabs: The image of the crystal axes, voltages, and polarization has been updated today (6/14/2013). Thanks again for bringing it to our attention.
bdada  (posted 2011-11-04 11:37:00.0)
Response from Buki at Thorlabs: Thank you for your inquiry. For 925nm I would recommend the –C2 units which have the AR coating for 900-1250nm. We have sent you additional information on the reflection from each surface - it is much less than 0.5% over the 900-1250nm range. Please coontact TechSupport@thorlabs.com if you have further questions.
yuilon  (posted 2011-11-02 09:30:26.0)
I concern the product EO-PM-NR-C2, how much power lost inside EOM assuming in coming laser is CW 925 nm with power 1 W/mm2?
bdada  (posted 2011-09-15 14:55:00.0)
Response from Buki at Thorlabs: Yes, the EO-AM-NR-Cx modulators will work for a pulsed laser. The primary concern, however, is the optical power level that causes photorefractive damage to the Lithium Niobate (LN) crystal. The LN crystals used in the Thorlabs EO modulators are MgO doped which increases the photorefractive damage level to 2W/mm2 @ 532 nm and 4W/mm2 @ 1064 nm. The photorefractive damage level is highly dependent on wavelength, decreasing rapidly at wavelengths below 532 nm. For the C1 wavelength range (600-900 nm) it would be conservative to use the 2W/mm2 damage threshold level. For the C2 wavelength range (900-1250 nm), use the 4W/mm2 damage threshold level. These damage power levels are for CW power. The question is how does this scale to peak power levels for pulsed operation. It is very difficult to answer this question, there is no simple answer because in the end it will depend upon pulse width, duty cycle, peak power and wavelength. Based upon some measurements that we have been making recently to address this issue, it appears that for short pulses (< 1 ns) and low duty cycle (< 0.2%) pulsed lasers, the damage level for the average power is approximately 50% of the CW damage level. So, for example, the damage threshold for a short pulse, low duty cycle laser in the 600-900 nm range is an average power of approximately 1W/mm^2. Please contact TechSupport@thorlabs.oom if you have further questions.
cyjiang  (posted 2011-09-13 09:19:48.0)
I want to know whether the EO-AMNR-C1 and C2 could work properly for pulsed laser. The pulse width is 2 ps and the average power of the pulse is 1 mW. Thank you very much.
bdada  (posted 2011-08-22 16:48:00.0)
Response from Buki at Thorlabs: Thank you for your feedback. We have contacted you to verify the details of your set up.
eexjw1  (posted 2011-08-22 11:25:05.0)
I tested the stability of EO-PM-NR-C1 before it is installed into the system. The modulation frequency from HV amplifier is 1kHz at 120V, laser power is 15 mW, with a diameter of 1mm, which are all within the range for EOM use. The problem is that the signal has a sinusoidal drift with a period of 15 ~ 20 min, and the signal goes to absolutely zero during the drifting. What may be the reason for this? Has this ever happened before?
jjurado  (posted 2011-08-12 13:35:00.0)
Response from Javier at Thorlabs ti cev136: I will contact you directly to assist you with your application.
cev136  (posted 2011-08-12 09:52:41.0)
Does not work at DC for 400nm light.
jjurado  (posted 2011-08-02 15:08:00.0)
Response from Javier at Thorlabs to cyjiang: At a power output on 1 W and 1 mm diameter, the power density is then 1 W/[pi x (0.5mm)^2] = 1.3 W/mm^2, which is below the maximum recommend input of 4W/mm^2 at 1064 nm. The EO modulator should work well under this condition.
cyjiang  (posted 2011-08-02 13:48:42.0)
In the manual it is said that the Maximum Optical Power Density of EO-AM-NR-Cx is 2W/mm2 at 532nm and 4W/mm2 at 1064 nm. We have a 1064 nm laser beam with a power of 1 Watt and a diameter of 1 mm. Would it work properly at such condition? Or will there be any problem for handling such laser beam by using these modulators?
jjurado  (posted 2011-06-23 20:02:00.0)
Response from Javier at Thorlabs to cumn333: Thank you very much for contacting us. We currently do not have data regarding the performance of our EO modulators when subjected to femtosecond laser pulses. Nonlinear effects such as self-focusing and self phase modulation might take place when using a femtosecond source, but we unfortunately do not have a quantitative analysis for these effects and how they affect the LN crystals. However, the main concern is the potential photorefractive damage that will most likely occur at the 900 nm wavelength and 2 W power range. Based on the damage threshold guidelines for these modulators (4W/mm^2 at 1064 nm), these modulators will most likely not work for your application. I will contact you directly for further assistance.
cumn333  (posted 2011-06-21 14:35:31.0)
I wonder if your EO phase modulator can work with femtosecond pulses from Ti:sapphire lasers. For example, power=2Watt, Wavelength=900nm, Reprate=80MHz, pulse duration = 150 fs. I am worried about that the light intensity is strong enough to cause nonlinear interaction with the crystal. Customer Email: cumn333@yahoo.com This customer would like to be contacted.
jjurado  (posted 2011-05-06 16:47:00.0)
Response from Javier at Thorlabs to bradoptics: Thank you very much for contacting us with your request. The term "broadband" is used to describe the operating wavelength range, which, for the EO-AM-NR-C4, is 400-600 nm. Regarding the bandwidth, the broadband modulators can operate from DC to 100 MHz. I will contact you directly for further support.
bradoptics  (posted 2011-05-06 14:52:55.0)
I had a question about the bandwidth of the E0-AM-NR-C4. Its listed as "broadband" on the spec sheet. Could I use it from DC to 1MHz?
jjurado  (posted 2011-03-30 10:23:00.0)
Response from Javier at Thorlabs to carlos.camargo: Thank you very much for contacting us. The EO-AM and EO-PM electro-optic modulators are designed for freespace input (and output). They have an input clear aperture of 2 mm. I will contact you directly for further assistance. You can also check the manual for more information: http://www.thorlabs.com/Thorcat/15900/15956-D02.pdf
carlos.camargo  (posted 2011-03-30 09:20:14.0)
A dummy question: How does the light enter in the EOM? By fiber or directly the light beam? How does it out?
Thorlabs  (posted 2010-07-12 15:05:53.0)
Response from Javier at Thorlabs to martensites: thank you for your feedback. We have not tested the maximum peak-to-peak voltage that the EO modulators can withstand. However, we do know that the crystal should perfom well and without any risk of damage at an input of +/- 240 V.
martensites  (posted 2010-07-12 01:57:57.0)
Please let me know the range of operating voltage of the EOM. Is it possible working on +- 240 V? (+-half wave voltage)
jjurado  (posted 2010-06-01 21:26:42.0)
Response from Javier at Thorlabs to andriyc: the common term used in amplitude/phase modulators is contrast ratio, which depends on factors such as input beam diameter, alignment through the crystal, extinction ratio of polarizers, and linewidth of laser source. The key parameter will be beam diameter; at ~1mm, contrast ratios on the order of 20:1 are typical. As the beam diameter decreases to around .5mm, typical values are on the order of 50:1. Also, focusing the beam can lead to higher contrast ratios, however you must be careful not to damage the crystal by incurring high power densities. You can also use pinholes to increase the contrast ratio well above 100:1. The C4 in the EO-AM-NR-C4 defines the anti-reflective coating, which covers 400-600nm, with a reflectivity < 0.5%. Though the reflectivity will not be as low, this modulator can still be used at 650nm with low reflectivity, in the order of <2%.
andriyc  (posted 2010-05-31 09:42:45.0)
What is the extinction ratio (of polarizations) for EO Amplitude Modulators (for ex. EO-AM-NR-C4). Also, could EO-AM-NR-C4 be used for modulating wavelengths up to 650 nm? The division into versions Cx comes only from anti-reflection coating?
Adam  (posted 2010-05-26 17:09:56.0)
A response from Adam at Thorlabs to andriyc: The amplitude modulators can be used to modulate the polarization of the light as long as the incoming light is polarized.
andriyc  (posted 2010-05-26 14:03:03.0)
Is it possible to use Thorlabs EOM for modulation of the polarization?
Adam  (posted 2010-04-21 08:54:43.0)
A response from Adam at Thorlabs to pmd: At this time, there are no plans to add BBO or KDP crystals in our modulator line. However, I like the idea of offering modulators that work in the UV range and will mention your idea to our engineers as a customer inspired new product idea.
pmd  (posted 2010-04-21 00:52:49.0)
When will you add other crystals, like BBO and KDP to have modulators that are good in the UV? Thanks, Pedro.
Greg  (posted 2010-04-13 17:16:01.0)
A response from Greg at Thorlabs: We have added specifications to the Specs tab regarding the High Q Resonant option modulators. More information will be added on these modulators shortly.
user  (posted 2010-01-16 13:18:45.0)
The presentation mentions but then doesnt provide any details on the: High Q Resonant Option. Are there specifics that could be added to help the reader understand what Thorlabs has to offer.
apalmentieri  (posted 2009-12-15 13:05:20.0)
A response from Adam at Thorlabs: At this time we do not offer high voltage amplifiers that will operate with bandwidths greater than 1MHz. If your modulation frequency is fixed, you may be able to use a resonant modulator. This will make your Q factor ~10 so your halfwave voltage will be ~20V @633nm. This will be much more manageable in terms of finding the appropriate driver electronics. I will email you with more information about pricing and lead time for these custom products. Please note that if you need to modulate from 20Mhz -50MHz a broadband modulator may be necessary and it becomes more difficult to find the appropriate driver electronics. I will email you with some suggestions for these as well.
stephanos  (posted 2009-12-14 14:22:12.0)
I noticed that although your modulators have a bandwidth of up to 100Mhz, the voltager amplifier you provide only has a bandwidth of 1MHz. I am interested in a broadband Amplitude modulator that uses EO Modulators in the visible wavelength (400nm-670nm) that I can pulse modulate (digital input signals) and the resultant optical output can be pulse widths ~ 2nsec at rep rates of 10MHz-50MHz, with good extinction ratio (better than 200:1). Does Thorlabs have such a solution for me? Feel free to contact me directly on my cell (408) 849-6619 or via e-mail: Stephanos@Oramic.com
Laurie  (posted 2008-12-09 10:27:02.0)
Response from Laurie at Thorlabs to lsandstrom: Thank you for your feedback. The units are radians.
lsandstrom  (posted 2008-12-09 10:15:55.0)
What is the units on the axis in Fig. 1 in the graph tab?
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EO振幅変調器

Vpi
Click to Enlarge
振幅変調器の結晶の方向

電気光学振幅変調器 (EO-AM)は、RF入力コネクタ付きのコンパクトな筐体に収納された2つの整合されたニオブ酸リチウム結晶(右図参照)から構成されたポッケルスセル型変調器です。結晶に電圧を印加することによって、屈折率(常光および異常光)が変わり、電界に依存する複屈折が生じ、ビームの偏光状態が変化します。EO結晶は、印加電圧に比例するリターダンスを持つ可変波長板として機能します。出射部に線形偏光子を置くことによって、偏光子を貫通する光の強度は、印加電圧に比例して正弦波波状に変化します。

-C4バンド(400~600 nm)で動作する変調はすべて、数Hz以上のAC変調でのみご使用ください。酸化マグネシウム(MgO)添加ニオブ酸リチウムはこの波長域の光に感度があるため、印加されたDC電圧が徐々に打ち消されます。光の強度が大きいほど、DC電圧が打ち消される速度が速くなります。従って、変調器を所定の動作点で動作させるためのバイアスとしてDC電圧をかけることはできません。その代わりに調整可能な波長板を組み合わせて変調器を所定の動作点で動作させることはできます(適切なバイアスの方法についての詳細は「実験データ」タブをご覧ください)。

+1 数量 資料 型番 - ユニバーサル規格 定価(税抜) 出荷予定日
EO-AM-NR-C4 Support Documentation
EO-AM-NR-C4EO振幅変調器、波長:400~600 nm
¥410,836
7-10 Days
EO-AM-NR-C1 Support Documentation
EO-AM-NR-C1EO振幅変調器、波長:600~900 nm
¥410,836
Today
EO-AM-NR-C2 Support Documentation
EO-AM-NR-C2EO振幅変調器、波長:900~1250 nm
¥410,836
7-10 Days
EO-AM-NR-C3 Support Documentation
EO-AM-NR-C3EO振幅変調器、波長:1250~1650 nm
¥410,836
7-10 Days
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EO位相変調器

当社のEO位相変調器は、直線偏光した入射光に可変位相シフトを与えます。入射光は、結晶にZ軸に相当する垂直方向に沿った直線偏光です。RF入力の電圧はZ軸の電極に印加されると、それによって結晶の異常光屈折率が変化し、光信号に位相シフトが生じます。

制御信号はDC信号または時間によって変化するRF信号となります。制御電圧が時間によって変化する場合、光の周波数は変調され、基本周波数のエネルギの一部は変調周波数の整数倍だけ基本周波数から分離された側波帯に変換されます。側波帯に変換されるエネルギの量は、変調の深さによって決まります。右のグラフは、変調深さの関数としての相対的な側波帯の強度を示しています。

+1 数量 資料 型番 - ユニバーサル規格 定価(税抜) 出荷予定日
EO-PM-NR-C4 Support Documentation
EO-PM-NR-C4EO位相変調器、波長:400~600 nm
¥396,163
Today
EO-PM-NR-C1 Support Documentation
EO-PM-NR-C1EO位相変調器、波長:600~900 nm
¥396,163
Today
EO-PM-NR-C2 Support Documentation
EO-PM-NR-C2EO位相変調器、波長:900~1250 nm
¥396,163
Today
EO-PM-NR-C3 Support Documentation
EO-PM-NR-C3EO位相変調器 、波長:1250~1650 nm
¥396,163
Today
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共振型電気光学(EO)変調器

共振型電気光学(EO)変調器は、高いQ値をもっており、一般的なファンクションジェネレータで駆動することができます。変調器内部にある高Q値共振型タンク回路が、標準的なファンクションジェネレータからの低いレベルのRF入力電圧を、幅広い変調が実現できる高電圧まで昇圧することができます。この結果、633 nmで半波長駆動電圧はわずかに15 Vで済みます。

共振型変調器には、位相変調型と振幅変調型があります。共振周波数20 MHzにて1 MHzの帯域幅で動作します。いずれにも600900 nmの波長に対応したC1コーティングが施されています。特注で、ARコーティングの指定と0.1100 MHz の共振周波数の指定が可能です。

+1 数量 資料 型番 - ユニバーサル規格 定価(税抜) 出荷予定日
EO-PM-R-20-C1 Support Documentation
EO-PM-R-20-C1共振型EO位相変調器、20 MHz、600~900 nm
¥469,526
Today
EO-AM-R-20-C1 Support Documentation
EO-AM-R-20-C1共振型EO振幅変調器、20 MHz、600~900 nm
¥498,872
7-10 Days
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グラントムソン偏光子取付けアダプタ、EO変調器用

EO-PMT Polarizer Mounting Adapter
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偏光子取付けアダプタEO-PMT
  • GTH5M取付け用アダプタ、当社のEO変調器用
  • 回転することにより光路への出入りが可能
  • GTH5M用Ø13 mm開口
  • #2-56取付けネジとワッシャが付属

EO-PMTによって、グラントムソン偏光子(GTH5M)を当社の電気光学(EO)変調器へ簡単に取り付けることができます。このマウントでは取付け部が1つなので、偏光子を旋回させて光路へ出入りさせることができ、EO変調器のアライメントや調節に便利です。EO-GTH5Mには、グラントムソン偏光子(GTH5M)と取付けアダプタがセットになっています。

+1 数量 資料 型番 - ユニバーサル規格 定価(税抜) 出荷予定日
EO-PMT Support Documentation
EO-PMTグラントムソン偏光子取付けアダプタ
¥4,395
7-10 Days
EO-GTH5M Support Documentation
EO-GTH5Mグラントムソン偏光子取付けアダプタ、GTH5M付属
¥73,562
7-10 Days
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EO変調器用マウントアクセサリ

当社のEO変調器は、5軸ステージPY005(/M)、ブラケットFT-EOMAならびにベースPY005A1(/M)を用いて50.8 mmのビーム高とするか(左)、直接ステージPY005(/M)に取り付ける(右)ことが可能です。

FT-EOMA EO Modulator Application Shot
Click to Enlarge

EO変調器をFiberBenchに取り付けるためにアダプタFT-EOMAを使用
  • 5軸調整機能付き小型プラットフォーム
  • アダプターブラケット:EO変調器をプラットフォームまたは長さ70 mm超のFiberBenchに取り付け
  • 取付ベースPY005A1/MにEO変調器を取り付け、PY005/MとFT-EOMAもあわせて使用すると、ビーム高は50.8 mm(公称値)
  • 全ての取付アダプタには取付用ネジが付属

PY005/Mは5自由度の小型プラットフォームです。5つのアクチュエータのうち、2つがヨーとY軸、2つがピッチとZ軸、1つがX軸を調整します。ヨーとY軸のアクチュエータに接着剤で取り付けられている2つのロック用カラーF19SC1は、これらのアクチュエータがオーバードライブをしないようハードストップとして機能します。ピッチ、X軸、Z軸のアクチュエータは底部に内孔があることによりオーバードライブを防いでいます。 なお、ステージの総移動量が小さくなるため、ロック用カラーF19SC1をピッチ、X軸、Z軸のアクチュエータに使用することはお勧めしていません。こちらをクリックするとPY005/Mステージの詳細がご覧になれます。

EO変調器は、ステージ底面にあるザグリ穴を使用して直接PY005/Mに取り付けることも可能です(1番右の写真参照)。ザグリ穴には、ベースPY005A1/Mがステージの下に取り付けられている状態でもアクセスできます。またEO変調器はアダプターブラケットFT-EOMAを使用してステージに取り付けることも可能です(右から2番目の写真参照)。FT-EOMAを使用してEO変調器をステージに取り付け、ベースPY005A1/Mをステージの下に取り付けた場合、EO変調器の光軸高さは光学テーブルから50.8 mm(公称値)になります。

アダプターブラケットFT-EOMAを使用してEO変調器をFiberBenchに取り付けることも可能です。EO変調器を取り付けるベンチの長さは最低70 mm必要です。偏光子付きマウントアダプタ(EO-GTH5M)を組み込む場合にはさらに長いFiberBenchが必要となります。FiberBenchシステムのEO変調器には直線偏光モジュールの使用が適しています。右の写真は、EO変調器に多軸のFiberBenchFT-38X100直線偏光モジュールを各1つと、2つのFiberPortを組み合わせた使用例です。

+1 数量 資料 型番 - インチ規格 定価(税抜) 出荷予定日
PY005 Support Documentation
PY005小型5軸ステージ、デッキ高27.4 mm (1.08インチ) (インチ規格)
¥61,954
7-10 Days
PY005A1 Support Documentation
PY005A1溝付き取付けベースアダプタ、PY005用、デッキ高1.44インチ(インチ規格)
¥4,192
7-10 Days
+1 数量 資料 型番 - ユニバーサル規格 定価(税抜) 出荷予定日
FT-EOMA Support Documentation
FT-EOMAアダプタ、EO変調器&FiberBenchまたはPY005/M用
¥7,854
Today
+1 数量 資料 型番 - ミリ規格 定価(税抜) 出荷予定日
PY005/M Support Documentation
PY005/M小型5軸ステージ、デッキ高27.4 mm (ミリ規格)
¥61,954
Today
PY005A1/M Support Documentation
PY005A1/M溝付き取付けベースアダプタ、PY005/M用、デッキ高36.6 mm(ミリ規格)
¥4,192
Today