Optically biased and controlled signal processing in silicon photonics.

Area of Science:

• Photonics and Optical Engineering
• Integrated Circuits
• Signal Processing

Background:

• Traditional signal processing often relies on electrical control, which can be limited by bandwidth and power consumption.
• Silicon photonics offers a promising platform for high-speed optical signal processing due to its compatibility with existing semiconductor manufacturing.
• Efficient optical control mechanisms are crucial for advancing integrated photonic systems.

Purpose of the Study:

• To demonstrate optically biased and controlled signal processing within a commercial silicon photonics integrated circuit (IC) process.
• To showcase the use of wavelength-division multiplexing (WDM) for carrying separate data and control signals.
• To experimentally validate two specific applications: an amplitude modulator and a two-tap sequence detector.

Main Methods:

• Utilized a commercial silicon photonics foundry process for fabricating the integrated circuits.
• Employed wavelength-division multiplexing (WDM) to separate optical data and control signals.
• Converted optical control signals to electrical voltages using series-stacked photodiodes operating in photoconductive mode.

Main Results:

• An amplitude modulator was demonstrated, requiring only 0.25 mW of optical control power to achieve a 15 dB tuning range of optical output power.
• A two-tap sequence detector was successfully implemented, capable of mapping symbols from various modulation formats (OOK, PAM-3, PAM-4) to distinct levels.
• The sequence detector required a maximum of 5 mW optical control power for calibration and biasing.

Conclusions:

• Optically controlled signal processing is feasible and efficient using standard silicon photonics IC processes.
• The demonstrated scheme offers low optical control power requirements for key functionalities like amplitude modulation and sequence detection.
• The proposed approach is scalable for detecting longer sequences and supporting more complex modulation formats in future photonic systems.