Ultra-low-crosstalk silicon switches driven thermally and electrically.

Area of Science:

• Photonics and Optical Engineering
• Materials Science and Engineering
• Computer Engineering

Background:

• Silicon photonic switches are vital for managing increasing data traffic in datacenters due to their efficiency and bandwidth.
• Crosstalk in large-scale photonic circuits remains a significant challenge, compromising signal integrity.
• Existing Mach-Zehnder Interferometer (MZI) switch designs require further optimization to minimize crosstalk.

Purpose of the Study:

• To present novel silicon Mach-Zehnder Interferometer (MZI) switch designs with ultra-low crosstalk.
• To optimize switch fabrics at both device and circuit levels for crosstalk suppression and reduced complexity.
• To demonstrate the effectiveness of harnessing self-heating effects for improved MZI switch performance.

Main Methods:

• Developed two silicon Mach-Zehnder Interferometer (MZI) switch designs: one thermo-optic (T-O) and one electro-optic (E-O).
• Optimized switch designs at the device and circuit levels to minimize crosstalk.
• Utilized the self-heating effect in a carrier-injection-based MZI switch to create phase shifters for matched insertion loss.

Main Results:

• Achieved an ultra-low crosstalk ratio below -40 dB for both T-O and E-O switches.
• Demonstrated an on-chip loss of <5 dB and a switching time of 500 µs for the T-O switch.
• Showcased an on-chip loss of 8.5 dB and a switching time <100 ns for the E-O switch, with successful 50 Gb/s data transmission.

Conclusions:

• The proposed silicon MZI switch designs effectively suppress crosstalk, enhancing signal integrity in photonic circuits.
• The novel use of self-heating effects in E-O MZI switches offers a promising method for achieving arbitrary phase differences and matched insertion loss.
• These ultra-low crosstalk silicon photonic switches hold significant potential for future high-capacity datacenter networks and optical communication systems.