Development Of 650nm Red Semiconductor Laser Chip With Fundamental Transverse Mode

Since the invention of semiconductor lasers,semiconductor lasers with high power and high beam performance have become the core devices in the fields of optical information storage,laser display,industrial laser and medical equipment due to their excellent photoelectric conversion efficiency and flexible wavelength emission range.With the gradual deepening of basic research,visible light semiconductor lasers are facing new development opportunities.650 nm edge-emitting semiconductor lasers have been widely used in laser indication equipment,laser processing equipment,optical sensing devices,optical communications and medical devices due to their good optical parameters,excellent cost performance and efficient photoelectric conversion rate.In order to meet the new market requirements,improving the photoelectric conversion efficiency of semiconductor lasers and the lateral fundamental mode purity of output have become one of the hot spots in semiconductor laser device research and industrial technology development.In this context,this thesis mainly studies the theory,design,process preparation and device due to optimize performance of high power and high beam quality red semiconductor lasers based on the characteristics of AlGaInP / GaInP650 nm semiconductor lasers.The main contents are as follows:(1)The existing mode-control structure basically relies on the realization of narrow ridge waveguide structure,but the output of laser single fundamental mode is not realized.In this paper,the basic narrow ridge waveguide structure is analyzed,and the number of optical field modes allowed in the waveguide is studied.According to the distribution of optical field modes obtained by simulation,it is found that the fundamental mode field is distributed in the center of the waveguide,while the high-order mode field is roughly distributed on both sides of the waveguide.The existence of high-order modes is an important factor in affecting the spot.(2)Based on the carrier distribution and the distribution of each optical mode field obtained by simulation,a red semiconductor edge emitting laser with mode-control structure with trenches is designed.Based on the 650 nm ridge waveguide semiconductor laser structure,trenches are added on both sides of the narrow ridge waveguide as a mode control structure.The oscillation threshold of the high-order mode is improved by the introduction of microstructure,which plays a role in regulating the optical mode.(3)During the experiment,it is found that the trench may not only suppress the oscillation of the high-order mode,but also affect the fundamental mode oscillation,thus affecting the optical power of the chip.Therefore,the influence of the position of the trench structure is analyzed by simulation software,and the high output power is guaranteed as much as possible the well control effect.(4)According to the industrial characteristics of AlGaInP,the slope on both sides of the ridge structure is inconsistent,so it will affect the diffusion of carriers,thus affecting the oscillation of higher-order modes.In order to study the influence of the slope on both sides of the ridge on the optical field distribution in the waveguide,the left-trench structure(the steep slope side),the right-trench structure(the gentle slope side)and the bilateral-trench structure are designed for simulation and comparative analysis.(5)On the one hand,the mode-control structure prevents carrier diffusion and limits the light excitation between the trenches as much as possible.At the same time,the structure increases the loss of the high-order side mode by causing the refractive index change of the waveguide structure,thereby increasing the threshold gain difference between the fundamental mode and the high-order mode,forming a high-order mode loss region in the high-order mode oscillation region.The threshold of the high-order mode is increased,and the only fundamental mode emitting is realized to reduce the stray light in the slow-axis spot of the laser.Finally,the 650 nm semiconductor laser chip prepared in this paper is tested.The measured divergence angle is8.5°.The threshold current and slope efficiency are 10.3 m A and 1.39 W/A respectively,and the output power is 41.5 mW.