GaAs Based V-coupled Cavity Semiconductor Tunable Laser

Semiconductor tunable lasers are widely used in optical communications,sensor detection and other fields due to their small size,long life and high photoelectric conversion efficiency.Among them,the V-coupled cavity tunable laser has the advantages of high side mode suppression ratio and wide tuning range.What's more,by virtue of its unique mode selection structure-half-wave coupler,it avoids multiple epitaxy or grating etching,and the device is simple to manufacture.Tunable lasers based on the Ga As/Al Ga As material play an important role in lidar,blood testing and other fields.These fields always have high performance,low cost,and easy integration requirements for tunable lasers.This is also the advantage of V-coupled cavity tunable lasers.Therefore,this thesis focuses on Ga As-based V-coupled cavity tunable lasers,and the laser design and device fabrication process were studied.The following is the main content and conclusions of this dissertation:1)The structure design of V-coupled cavity laser: the key structures of V-coupled cavity laser,bending waveguide and half wave coupler,were designed and optimized.Firstly,based on the beam propagation method,a curved waveguide for the cleavage plane V-coupled cavity laser was designed.By optimizing its geometric parameters,the beam propagation loss was kept at about 15%.Then,the influence of coupling coefficient and coupling phase on the mode selection ability of V-coupled cavity laser was deeply analyzed,and a half wave coupler was designed.Finally,it was determined that the mode selection ability of V-coupled cavity laser could reach the maximum when the coupler length and width were about 19 ?m and 1.5 ?m,respectively.2)Improvement of tuning performance of V-coupled cavity laser: Based on the temperature distribution of V-coupled cavity laser in the wavelength tuning process,a scheme of adding heat insulation structure was proposed to improve the tuning efficiency of the laser.By establishing the temperature distribution model and thermal stress distribution model of V-coupled cavity laser,the influence of the thermal insulation structure in different positions of the laser was analyzed.The optimized thermal insulation structure could improve the laser tuning efficiency by 2.5 times.3)Fabrication and technology research of V-coupled cavity laser: Based on the semiconductor manufacturing processing,the V-coupled cavity tunable laser samples were fabricated,and the process parameters of each step involved in the fabrication were optimized.In the photolithography step,the alignment of the 2 ?m wide narrow ridge waveguide with the electrode pattern of the photomask was ensured by adding the auxiliary lithographic mark pattern;in the etching step,the combination of dry etching and wet etching was adopted to ensure the accurate height and good appearance of the ridge waveguide.The results show that the output wavelength of the laser was 946.15 nm,the side mode suppression ratio was20 d B,the threshold current was 24 m A,the output power was 20 m W,and the linewidth was0.06 nm.