Study Of High Efficiency High Power Semiconductor Laser

In recent 20 years multimode semiconductor diode lasers have achieved higher power and higher power conversion efficiency (efficiency for short) allowing them transite from specialty scientific items to pump sources for solid state laser used in factories. High efficiency devices are less costly for customers to operate since they can achieve higher power and longer lifetime. Increase efficiency for diode laser becomes very important due to strong demands at market .We mainly discuss how to improve efficiency of 808nm diode laser. We analyze efficiency formula theoretically and increase efficiency by decreasing turn-on voltage, serial resistance and threshold current. Use AlGaAs in waveguide and cladding layer and graded doping density in n-type waveguide can decrease turn-on voltage and serial resistance based on theoretical analysis and software simulation. Modify quantum well structure can decrease threshold current and increase power. We choose GaAsP tensile stain quantum well by comparing kinds of quantum wells. Since threshold current strongly depend on splitting between subbands in valence band of quantum well, we use eight band k·p theory to analyze band structure of GaAsP quantum well. From numerical calculation when exciting 808nm. In 14nm width GaAsP quantum well, splitting between first subband of light and heavy holes is equal to splitting between first and second subbands of light hole. Influence between subbands for first subband of light hole is minimized. Threshold current of diode laser can be minimized.Diode laser with AlGaAs waveguide and cladding and 14nm GaAsP quantum well was grown by low-pressure metalorganic chemical vapor deposition (LP-MOCVD), then fabricate four different cavity length lasers. From laser test, turn-on voltage, serial resistance and threshold current of 1mm cavity length laser is 1.56V, 100m? and 203A/cm2, respectively. The efficiency of laser is 59.8% when work current is 2A.