Study On High Power 785nm Semiconductor Lasers

High power 785 nm semiconductor lasers have great important application in DPAL, high precision measurement technology and so on. But there’re less researches on 785 nm LDs. This paper focuses on the high brightness application of 785 nm LD and design an extreme asymmetric structure laser. We analyses influence of quantum well number, cavity length, active layer and thickness of waveguide on threshold current density. The total thickness is designed as 0.32μm and the thickness of p-waveguide is only 0.07μm. Compared with the traditional asymmetric structures, the design not only pull the peak position of mode field far apart from the active region, but also improve the threshold power of COD. The thickness of p-waveguide is reduced greatly to decrease optical absorption and make the heat dispersion better under high power working condition.The reliability study of high power diode lasers is always focused. The non-injection structure is a common method to improve the threshold power of COD, the thermal temperature rise near facet region can be well controlled. The article gives the temperature profile of LD active region with different width of non-injection regions near cavity facet. Results indicates that the temperature rise of facet has a great impact on the reliability of the laser, and proved that the temperature of the facet can decrease effectively by nonabsorption region design. The temperature drop provides an advantage for suppressing the non-radiation recombination and optical absorption to improve the COD threshold.Au/Ni/AuGe/Ni for n-type ohmic contact with 100nm/45nm/100nm/5nm thickness has been prepared to optimize the serial resistance and enhance the characteristics of the laser output. The morphology by the electron microscope is observed, and the contact resisivity is calculated by method of RTLM. The results show that the annealing temperature has a significant effect on characteristics of the ohmic contact. The best condition for the n-GaAs ohmic contact by the Au/Ni/AuGe/Ni is obtained.