Electro-optic-waveguide frequency translator in LiNbO(3) fabricated by proton exchange

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Optical waveguide devices are crucial for modulating light signals.
• Lithium niobate (LiNbO3) is a key material for electro-optic modulators.
• Proton exchange is a common technique for fabricating optical waveguides.

Purpose of the Study:

• To fabricate and characterize an optical waveguide phase modulator on X-cut LiNbO3.
• To evaluate the performance of the modulator as a serrodyne optical-frequency translator.
• To investigate the effect of DC bias voltage on modulator performance.

Main Methods:

• Fabrication of the optical waveguide using proton exchange in benzoic acid on X-cut LiNbO3.
• Operation of the device as a serrodyne optical-frequency translator.
• Measurement of shifted-signal to image-signal discrimination and response to DC bias.

Main Results:

• The fabricated phase modulator achieved a shifted-signal to image-signal discrimination of 52 dB for a 4-MHz frequency shift.
• A sawtooth driving signal amplitude of 10 V peak to peak was used.
• Application of DC bias voltage, regardless of polarity, significantly reduced transmitted light intensity.

Conclusions:

• The proton-exchanged LiNbO3 waveguide phase modulator functions effectively as a serrodyne optical-frequency translator.
• The device exhibits excellent signal discrimination capabilities.
• DC bias voltage has a detrimental effect on light transmission, requiring careful consideration in practical applications.