APD direct detection receiver OEIC operating 14.1 dB above the shot noise quantum limit

Area of Science:

• Optoelectronics
• Integrated Circuit Design
• Photonics

Background:

• Direct detection receivers are crucial for optical communication systems.
• Avalanche photodiodes (APDs) offer potential for enhanced sensitivity compared to PIN photodiodes.
• High-voltage CMOS technology enables integration of sensitive photodetectors.

Purpose of the Study:

• To present a novel optoelectronic integrated circuit (OEIC) receiver featuring a dot-cathode avalanche photodiode (APD).
• To evaluate and compare the sensitivity of the APD-based receiver against a reference PIN photodiode receiver.
• To assess the performance of the APD receiver in terms of its proximity to the shot noise quantum limit.

Main Methods:

• Integration of a dot-cathode APD and a PIN photodiode on the same 180 nm high-voltage CMOS wafer.
• Utilizing an identical integrate-and-dump source-follower front-end for both photodiode receivers.
• Experimental characterization of receiver sensitivity at 642 nm wavelength, 100 Mb/s bit rate, and 80% RZ OOK modulation.

Main Results:

• The APD receiver achieved a sensitivity of -56.6 dBm at a bit error rate (BER) of 0.002.
• This sensitivity is 14.1 dB from the shot noise quantum limit, corresponding to an average of 71 photons per bit.
• A minimum normalized sensitivity improvement of 4 dB was observed for the APD receiver over the PIN receiver.

Conclusions:

• The developed APD receiver OEIC demonstrates high sensitivity suitable for advanced optical communication.
• The integration in 180 nm high-voltage CMOS is effective for realizing sensitive photodetector circuits.
• The APD receiver shows significant performance advantages over PIN receivers, approaching quantum-limited detection.