Study Of High Power Semiconductor Laser With Low Threshold Current

High power semiconductor laser is widely used in many fields. In recent year, researchers are focus on increasing the output power, improving optical beam quality, reducing threshold current densities and son on. In order to achieve these goals, people can do more work on structure design, epitaxial growth, coating and packaging.Large optical cavity is the most effective way to improve the output power. By increasing the lateral size of light spot, large optical cavity decreases luminous power densities and optimizes optical beam quality. However, large optical cavity reduces the optical confinement factor of active area and worsens the threshold current densities. In order to resolve the contradiction between large optical cavity and low threshold current densities, this paper designs a 980 nm semiconductor laser with a new multiple quantum wells and super large optical cavity.In the new multiple quantum wells, the band gap of waveguide layer is narrower than that of the barrier?Besides, the ability of limiting the carriers of multiple quantum wells is more effective than single quantum well, so multiple quantum wells can decrease the threshold current densities. Asymmetric waveguide structure is also adopted to expand light field. Asymmetric waveguide can also reduce internal loss and bulk resistance which improve the performance of semiconductor laser. At last, it need to adjust the thickness and refractive index of all layers.MOCVD is adopted for epitaxial growth. In this paper, the semiconductor processes include lithography, etching, grow SiO₂, spattering and so on. Optimizing the fabrication of electrode is also involved.All semiconductor lasers don't coat facet film. The test results are below: threshold current densities is 168.42A/cm², emission wavelength is 965.8nm, vertical divergence angle is 15.6° and horizontal divergence angle is 4.2°.