Integrated fiber optical receiver reducing the gap to the quantum limit

Area of Science:

• Photonics
• Integrated Circuits
• Optical Communications

Background:

• Single-photon avalanche diodes (SPADs) are crucial for sensitive optical receivers.
• Parasitic effects in SPADs can limit performance.
• CMOS technology integration offers miniaturization and cost benefits.

Purpose of the Study:

• To present experimental results of a SPAD-based optical fiber receiver.
• To improve photon detection probability (PDP) and receiver sensitivity.
• To demonstrate performance exceeding conventional receivers in CMOS technology.

Main Methods:

• Integration of a SPAD-based optical fiber receiver in 0.35 µm CMOS technology.
• Implementation of an array of four receivers to mitigate parasitic effects.
• Utilizing cascoded quenchers and a thick absorption zone to enhance PDP.

Main Results:

• Achieved sensitivities of -55.7 dBm at 50 Mbit/s and -51.6 dBm at 100 Mbit/s (635 nm wavelength, BER 2x10^-3).
• Demonstrated superior sensitivity compared to linear-mode APD receivers in the same CMOS technology.
• Results indicate performance close to the quantum limit for direct detection optical receivers.

Conclusions:

• The developed SPAD optical receiver offers significant advancements in sensitivity and performance.
• The design effectively addresses parasitic effects and enhances PDP.
• This work paves the way for highly sensitive, quantum-limited optical receivers integrated in standard CMOS.