Research On Key Technologies Of Near-infrared Horizontal Cavity Surface-Emitting Semiconductor Lasers

Due to its outstanding advantages such as high beam quality,narrow spectral linewidth,and good wavelength stability,horizontal cavity surface-emitting distributed feedback(SEDFB)semiconductor lasers has been one of the research hotspots of researchers.This thesis focuses on the key technology of Ga As-based horizontal cavity surface-emitting distributed feedback semiconductor lasers.The main idea is to improve the quality of the grating and the optical output characteristics of SE-DFB semiconductor lasers by designing and optimizing the second-order grating structure.The main research contents are as follows:(1)Research on structural parameters of second-order grating.In order to lock the lasing wavelength of the horizontal cavity SE-DFB semiconductor laser accurately and improve the optical output characteristics of the device,the influence of the structural parameters of the second-order grating(period,duty cycle,etched depth)on the output characteristics of the laser is analyzed.So as to achieve the laser emission wavelength at 940 nm band,the grating parameters with a period of 278 nm,a duty cycle of 0.4 and an etching depth of 280 nm are finally determined.(2)Study on the influence of the second-order grating morphology on the coupling coefficient of the grating.In order to optimize the structure of the second-order grating,the coupling factors of gratings with different shapes(rectangular,trapezoidal,triangular)are compared,and the influence of the second-order grating shape on the coupling coefficient of the grating is analyzed.By comparing the reflection spectra of gratings with different shapes,the influence of the grating shape on the narrow line width and the longitudinal mode of the grating is explored.The side-mode suppression ratio,output power and slope efficiency of the horizontal cavity SE-DFB semiconductor lasers with gratings of different shapes are simulated.It is concluded that the optical output characteristic of the rectangular grating SEDFB semiconductor laser is the best.(3)Design and optimize the epitaxial structure of the horizontal cavity SE-DFB semiconductor laser.The ideal lasing wavelength of the laser can be obtained by adjusting the material,composition,thickness and other parameters of the quantum well.The asymmetric waveguide structure is designed to achieve the optical field bias,and the optical field distribution is biased toward the active layer and the vicinity of the waveguide layer.The ridge waveguide structure is used to suppress the lateral current and reduce the threshold current of the laser.By using Simu Pics3 d software to simulate the epitaxial structure of horizontal cavity SE-DFB semiconductor laser,the optical gain of quantum well,the optical field distribution and current distribution of the epitaxial structure are obtained.(4)Fabrication and analysis of device.According to the simulated parameters of the rectangular grating SE-DFB semiconductor laser,combined with the fabrication of secondorder gratings,ridge-shaped waveguides,electrode and light exiting,as well as process steps such as cleavage and encapsulation,a rectangular grating SE-DFB semiconductor laser with a lasing wavelength of 940.3 nm is prepared.The line width of the device is 0.52 nm,the threshold current is 900 m A,and the surface emission power is 890 m W under continuous operation mode.