Low-loss chalcogenide photonic devices with a secondary coating method

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Traditional dry etching for photonic devices often leads to high sidewall roughness and transmission loss.
• Germanium-antimony-selenium (Ge-Sb-Se) chalcogenide waveguides and micro-ring resonators are crucial for integrated photonic applications.

Purpose of the Study:

• To introduce and validate a secondary coating method for improving Ge-Sb-Se photonic device performance.
• To reduce transmission loss and sidewall roughness in Ge-Sb-Se waveguides.
• To enhance the quality factor (Q-factor) of Ge-Sb-Se micro-ring resonators.

Main Methods:

• Fabrication of Ge-Sb-Se waveguides and micro-ring resonators using ultraviolet exposure/electron beam lithography and inductively coupled plasma etching.
• Application of a 10 nm-thick Ge-Sb-Se thin film via thermal evaporation as a secondary coating.
• Measurement of waveguide transmission loss and micro-ring resonator Q-factor before and after secondary coating.

Main Results:

• Secondary coating reduced waveguide sidewall roughness from 11.96 nm to 6.52 nm.
• Transmission loss decreased from 2.63±0.19 dB/cm to 1.86±0.11 dB/cm at 1.55 µm wavelength.
• The Q-factor of micro-ring resonators improved by 47.5% under consistent coupling conditions.

Conclusions:

• The secondary coating method is effective in fabricating low-loss Ge-Sb-Se photonic devices.
• This technique offers a feasible approach to enhance the performance of integrated chalcogenide photonic devices.
• Improved sidewall smoothness and reduced optical loss are key benefits for high Q-factor resonators.