Physics Lab Equipment

LEOI-34A Experimental System for Electro-Optic Modulation

LEOI-34A Experimental System for Electro-Optic Modulation


  • Enhanced experimental phenomena with drive voltage Vmax ≥ 1600 V

  • Clear process observation from uniaxial crystal to biaxial crystal

  • Observe and measure electro-optic modulation waveform

  • High sensitivity photoreceiver for stable waveform output

  • Electro-optic modulation technique demo


Electro-optic effect is a change in the refractive index of a crystal as induced by an electric field. By using a laser amplitude modulator employing the transverse electro-optic effect of a typical LiNbO3 crystal, students can


1. understand electro-optic effect and its applications

2. measure the half-wave voltage and electro-optic coefficient of crystals

3. observe a change in optical properties of crystals due to electro-optic effect

4. observe the interference of focused polarized light as caused by electro-optic effect

5. conduct demonstration of optical communication via electro-optic effect


This experimental system can be used to conduct the following experiments:


1. Study optical axis characteristics of LiNbO3 crystal in absence and presence of driving voltage
2. Observe electro-optic modulation phenomenon
3. Measure half-wave voltage and calculate electro-optic coefficient of electro-optic crystal
4. Demonstrate optical communication using electro-optic modulation technique

Parts and Specifications

Optical railLength: 0.8 m1
Main unitDrive voltage Vmax ≥ 1600 V with built-in speaker1
Diode laser4 mW at 650 nm with 2-D adjustable holder1
PolarizerIncl holder, 360° rotary, scale 1°, aperture 27 mm2
LiNbO3 crystalClear aperture: 5 mm × 5 mm with 3-D adjustable holder1
Laser power meter (LLM-1)

3-1/2 digits

Scale: 200 μW, 2 mW, 20 mW, 200 mW

Resolution: 0.1 μW

Photo diode detectorIncl 2-D adjustable holder, ±2.5 mm1
Beam expander lensIncl 2-D adjustable holder, 40 X1
λ/4 wave plateIncl holder, 360° rotary, scale 1°, aperture 27 mm1
White screen100 mm × 80 mm1
Audio sourceiPod nano1
CableBNC cables (3) and audio cable (1)4
Power cord
Instruction manual

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S: Source laser

P: Polarizer

C: LiNbO3 crystal

A: Analyzer

V: Voltage

D: Photo receiver

LEOI-34A Experimental System-2.jpg

Interference patterns of polarized light

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Effect of dc voltage bias on output characteristic of electro-optic crystal

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