Silicon-based traveling-wave photodetector array (Si-TWPDA) with parallel optical feeding

Area of Science:

• Photonics and Optoelectronics
• Integrated Silicon Photonics
• Semiconductor Device Physics

Background:

• Traveling-wave photodetectors (TWPDAs) are crucial for high-speed optical communication.
• Integrating multiple photodetectors in arrays can enhance performance but presents design challenges.
• Silicon photonics offers a scalable platform for optoelectronic device integration.

Purpose of the Study:

• To demonstrate silicon-based traveling-wave photodetector arrays (Si-TWPDAs) with parallel optical feeding.
• To achieve high optical saturation power while maintaining a large operation bandwidth.
• To optimize electrode and waveguide designs for improved photodetector performance.

Main Methods:

• Integration of multiple Germanium (Ge) photodetectors onto a silicon platform.
• Design of impedance-matched traveling-wave electrodes considering individual photodetector loading.
• Implementation of optical waveguide delay lines to balance electrical phase delay.
• Characterization of photocurrent, saturation power, responsivity, and bandwidth.

Main Results:

• Demonstrated Si-TWPDAs with 1, 2, and 4 integrated Ge photodetectors.
• Achieved maximum linear photocurrents of 16 mA, 38 mA, and 65 mA at -4V bias.
• Observed saturation powers of 40 mW, 100 mW, and 160 mW, respectively.
• Measured a 3-dB bandwidth of approximately 20 GHz for a 4-channel TWPDA.
• Extracted fiber access responsivity of ~0.42 A/W and intrinsic responsivity of ~0.82 A/W.

Conclusions:

• Si-TWPDAs with parallel optical feeding offer high optical saturation power and large bandwidth.
• The demonstrated devices show promising performance metrics for high-speed optical detection.
• The integrated approach provides a scalable solution for advanced photodetector arrays.