Research On Key Technologies Of Self-injection Locked Narrow Linewidth Laser

With the continuous development of laser technology,high-performance semiconductor lasers with narrow linewidths are widely used for applications such as atomic clocks,fiber optic sensing,laser detection and measurement.However,due to factors such as the size and quality factor of the resonant cavity of semiconductor lasers,the linewidth of semiconductor lasers is usually in the megahertz range,which is far from meeting the requirements of high-precision applications.Therefore,the study of linewidth compression of semiconductor lasers has high research value and development potential.Among them,the self-injection-locked external cavity semiconductor laser with simple structure,large tuning range,and obvious linewidth compression effect can realize the miniaturization and large-scale manufacturing of semiconductor lasers.The focus of this thesis is to carry out research on linewidth compression based on optical resonant outer cavities,aiming to continuously improve the stability of the optical system,reduce the linewidth of the semiconductor laser and improve the stability of the output laser by adopting a new outer cavity,a new mechanical structure and a narrow linewidth laser system.The main research contents of this thesis are:1.This thesis presents a modeling analysis of the linewidth compression theory for semiconductor lasers.Firstly,based on the rate equation,the theoretical derivation of frequency locking and linewidth compression for V-cavity injection locking is carried out,and the factors affecting linewidth compression are analyzed.2.In this thesis,a new self-injection locked narrow linewidth laser system based on an FP cavity is designed,including a laser collimation system,an external cavity feedback system and a frequency tuning system.As the key device for the experiment,a confocal FP cavity made of Ta Li O₃ material is designed,and the radius of curvature of the cavity is 6 mm.By analyzing the laser mode matching,a suitable lens combination is determined to achieve laser collimation and coupling of the laser into the FP cavity.The beam waist radius of the Gaussian beam coupled into the resonant cavity is 0.025 mm,which is close to the beam waist radius of the fundamental mode Gaussian beam in the resonant cavity.In addition,due to the need for precise control of the FP cavity,a new,compact mechanical structure was designed.3.This thesis designed a self-injection locked narrow linewidth system based on fiber resonant ring and waveguide resonant ring.By modeling the waveguide ring,the relationship between the incident light and the outgoing light is derived.Self-injection locking experiments based on a home-made fiber resonant ring were designed to obtain a linewidth of 20 k Hz.Finally,a waveguide resonant ring-based self-injection locking experiment was designed to measure the feedback power of the waveguide ring,and a maximum feedback power of 0.44μW was obtained,and the linewidth of the laser could be compressed to the order of a hundred hertz.