Suspended Si ring resonator for mid-IR application

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Semiconductor Devices

Background:

• Mid-infrared (MIR) photonics is crucial for spectroscopy and sensing.
• Silicon photonics offers a scalable platform but faces challenges in the MIR.
• Developing efficient MIR silicon waveguides and resonators is an active research area.

Purpose of the Study:

• To fabricate and characterize suspended silicon (Si) waveguides and ring resonators for the mid-infrared (MIR) wavelength range.
• To evaluate the performance of these devices in terms of quality factors and loss mechanisms.
• To identify strategies for improving device performance through fabrication process optimization.

Main Methods:

• Fabrication of suspended silicon waveguides and ring resonators.
• Characterization using tunable lasers and thermal tuning across MIR wavelengths (3.4 μm and 5.2 μm).
• Analysis of absorption loss via spectrum distortion, optical simulations, and all-optical modulation.

Main Results:

• Successful fabrication and characterization of suspended Si waveguides and ring resonators.
• Achieved loaded quality factors of 2700 at 5.2 μm and 7900 at 3.4 μm.
• Observed heat-induced spectrum distortion, indicating absorption losses.
• Identified surface scattering as the primary loss mechanism.

Conclusions:

• Suspended silicon structures are viable for MIR photonic applications.
• Device performance is limited by surface scattering losses.
• Improving fabrication processes can significantly reduce losses and enhance device efficiency.