| dc.description.abstract | Laser linewidth is one of the key indicators of laser performance, playing a
crucial role in various fields such as optical communication, LiDAR, and optical atomic
clocks. As technology advances, the requirements for laser linewidth have become
increasingly stringent. This thesis proposes a method to reduce laser linewidth using
self-injection locking technology. The method employs a microring resonator as the
external cavity of the laser, achieving mode-locking through energy feedback from
Rayleigh backscattering, further narrowing the laser linewidth. Compared to
commercially available external cavity lasers, this technique is more cost-effective and
highly compatible with complementary metal-oxide-semiconductor (CMOS)
fabrication technology, offering high integration density.
The thesis also introduces the fabrication process of the microring resonator. To
verify the impact of self-injection locking on laser linewidth, the thesis explores
linewidth measurement techniques in detail. Depending on the laser linewidth, it is
necessary to choose an appropriate length of delay fiber and adjust polarization during
measurement to achieve a Lorentzian profile in the spectrum. Additionally, the study
found that adjusting the distance between the coupling fiber and the laser to change the
power causes the linewidth spectrum to broaden as the power decreases, although
changes in power after the coupling fiber have little effect on the linewidth. The thesis
also compares the effects of different structures and waveguide materials on coupling,
ultimately selecting a low-confinement waveguide with a height of 100 nm as the
design for the external resonator. Finally, the thesis demonstrates how self-injection
locking can be achieved through various methods, successfully compressing the laser
linewidth to one-fifth of its original value. | en_US |