A 780 nm high-power and highly reliable laser diode with a long cavity and a thin tapered-thickness active layer

We have investigated conventional AlGaAs laser diodes with the uniform thickness active layer of various cavity lengths. It is recognized that the extension of the cavity length is effective in the improvement of the maximum output power, the temperature characteristics and the operating life in the high temperature conditions. We have newly fabricated a 780 nm, high-power laser diode having a 350-mu-m long cavity with a thin tapered-thickness active layer. The optical power density near the mirror facets, the thermal resistance, the current density and the carrier density are reduced by this structure. The laser emits over 100 mW of CW (continuous wave) output power even at temperatures up to 80-degrees-C. A maximum output power level of 160 mW is achieved at room temperature. The fundamental transverse mode is confirmed at least up to 120 mW. The full beam angles at half maximum power parallel (theta-parallel-to) and perpendicular (theta-perpendicular-to) to the junction plane are 11.5-degrees and 15.5-degrees, respectively. The high coupling efficiency between the laser beam and an optical lens is theoretically confirmed. The lasers have been operating with little degradation over 10,000 and 2,000 hours in 70-degrees-C, 30 mW and 50-degrees-C, 50 mW conditions, respectively.