Narrow-linewidth optical coherent oscillators in ultra-low loss silicon nitride
Licentiate thesis, 2025

In recent years, advancements in technologies such as optical coherent communication, precision measurement, optical detection and ranging, have raised the bar for the coherence, power, noise, and other key parameters of light sources. On-chip light sources have emerged as the ideal solution when small size, low weight, low power consumption and cost-effectiveness matter the most. Currently, integrated light sources include semiconductor lasers and chip-based optical parametric oscillators. However, due to their small cavity volume, both types suffer from high quantum noise, poor coherence compared to solid-state or gas lasers.
As a popular integrated photonic platform, silicon nitride has a significant potential for addressing these challenges since it has high nonlinearity, wide transparent window, and good compatibility with other materials. In our previous work, we have realized low-loss long waveguides and high-Q microring resonators. In this thesis, we further reduce the propagation loss of dispersion-engineered silicon nitride waveguides by smoothing the sidewall roughness. By periodically modulating the intrinsic and extrinsic Q factors of the microring resonator, we achieve an on-chip optical parametric oscillator with an output power of 215 mW and an intrinsic linewidth of 220 Hz. In addition, we suppress the frequency noise of both semiconductor lasers and soliton microsombs using an original self-injection locking method. We reduce the intrinsic linewidth of the semiconductor laser from 818 000 Hz to 135 Hz, and compress the intrinsic linewidth of comb lines of the soliton microcomb to below 1 Hz. These results pave the way for on-chip integration of high-power, narrow-linewidth lasers and optical parametric oscillators.

semiconductor laser

optical parametric oscillator

silicon nitride

narrow linewidth

frequency noise

low loss

integrated photonics

Kollektorn, A423, MC2
Opponent: Nils Johan Engelsen, Assistant Professor, Quantum Technology, Microtechnology and Nanoscience, Chalmers University of Technology

Author

Yi Sun

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Low-loss dispersion-engineered silicon nitride waveguides coated with a thin blanket layer

Optics InfoBase Conference Papers,;(2022)

Paper in proceeding

Yi Sun, Fuchuan Lei, Yan Gao, and Victor Torres-Company, High-power on-chip hyperparametric oscillator

Self-injection-locked optical parametric oscillator based on microcombs

Optica,;Vol. 11(2024)p. 420-426

Journal article

Narrow-linewidth and tunable parametric oscillator

2024 Conference on Lasers and Electro-Optics, CLEO 2024,;(2024)

Paper in proceeding

Driving Forces

Sustainable development

Innovation and entrepreneurship

Areas of Advance

Nanoscience and Nanotechnology

Subject Categories (SSIF 2025)

Nano-technology

Physical Sciences

Electrical Engineering, Electronic Engineering, Information Engineering

Infrastructure

Myfab (incl. Nanofabrication Laboratory)

Publisher

Chalmers

Kollektorn, A423, MC2

Online

Opponent: Nils Johan Engelsen, Assistant Professor, Quantum Technology, Microtechnology and Nanoscience, Chalmers University of Technology

More information

Latest update

1/28/2025