Silicon photonics plasma-modulators with advanced transmission line design

Area of Science:

• Photonics
• Electrical Engineering
• Materials Science

Background:

• Silicon Photonics Mach-Zehnder modulators face analog bandwidth limitations due to signal cross-talk and transmission line losses.
• Push-pull modulator designs often suffer from detrimental cross-talk between signal lines, limiting operational speed.
• Reducing resistive losses in transmission lines is crucial for improving modulator efficiency and bandwidth.

Purpose of the Study:

• To investigate novel transmission line designs for Silicon Photonics Mach-Zehnder interferometer depletion modulators.
• To overcome analog bandwidth limitations caused by cross-talk and reduce linear transmission line losses.
• To experimentally validate these concepts and assess their impact on electro-optic (E/O) bandwidth and insertion loss.

Main Methods:

• Development and implementation of two novel transmission line designs for Mach-Zehnder modulators.
• Experimental validation of the proposed concepts using Silicon Photonics technology.
• Characterization of E/O bandwidth, drive voltage, insertion loss, and transmission line loss models.

Main Results:

• Demonstrated an E/O -3 dBe bandwidth of 16 GHz with a 4V drive voltage in a dual-drive configuration.
• Achieved 8.8 dB on-chip insertion losses.
• Observed significant bandwidth improvements due to cross-talk suppression and an additional ~11% enhancement from reduced resistive losses.

Conclusions:

• The novel transmission line designs effectively suppress cross-talk, leading to substantial bandwidth enhancements in Mach-Zehnder modulators.
• Reduction in resistive transmission line losses further contributes to improved E/O bandwidth.
• Frequency-dependent loss models for loaded transmission lines and E/O bandwidth were fully verified, validating the study's findings.