Thermally annealed single-mode proton-exchanged channel-waveguide cutoff modulator

Area of Science:

• Photonics
• Materials Science
• Electrical Engineering

Background:

• Electro-optic modulators are crucial for optical communication and signal processing.
• Lithium niobate (LiNbO3) is a widely used material for electro-optic devices due to its excellent properties.
• Achieving low-voltage, high-performance modulators remains a key challenge.

Purpose of the Study:

• To report the first electro-optic cutoff modulator utilizing a thermally annealed single-mode proton-exchanged channel waveguide.
• To demonstrate reduced voltage requirements and improved modulation linearity.
• To assess the optical damage resistance of the fabricated device.

Main Methods:

• Fabrication of single-mode proton-exchanged channel waveguides in X-cut Y-propagating LiNbO3.
• Employing thermal annealing for fine-tuning refractive index changes and optimizing waveguide properties.
• Characterization of electro-optic modulation performance, including modulation depth, voltage swing, and linearity.
• Testing optical damage resistance under high laser intensity.

Main Results:

• Successfully created single-mode waveguides with channel widths as small as 2 micrometers.
• Achieved a significant reduction in the required voltage for electro-optic cutoff.
• Demonstrated a modulation depth of 97% with a total voltage swing of only 7 V, exhibiting high linearity.
• Observed no optical damage after 2-hour continuous exposure to 632.8-nm laser light at 10^4 W/cm^2.

Conclusions:

• The developed electro-optic cutoff modulator offers a promising solution for low-voltage, high-performance optical modulation.
• Thermal annealing is an effective technique for optimizing proton-exchanged waveguides in LiNbO3, enhancing modulation linearity and reducing operational voltage.
• The device exhibits excellent optical damage resistance, suitable for high-power applications.