835-nm GaAs/AlGaAs High-Power Laser Diode for Up-Conversion Fiber Lasers

High-power and high-efficiency 835-nm GaAs/AlGaAs single-quantum-well pumping laser diodes (LDs) for visible up-conversion fiber laser applications were fabricated. To achieve the highly efficient pump laser diode, a 1.0-μm-thick separate confinement heterostructure layer was inserted; namely, a large optical cavity (LOC) structure was adopted. This LOC structure minimizes the overlap between the optical modal fields and the highly doped cladding layers, which reduces the optical internal loss and increases the slope efficiency of the pumping LDs. LD arrays of 10 emitters with a 1,000-μm total emitter width were fabricated to evaluate the high-power LD characteristics and to check the feasibility of the up-conversion fiber lasers. A LD array with a small total emitter size of 1,000 μm operated at over 20 W with a very high 20-mW/μm optical power density. The threshold current and the slope efficiency of the LD array were about 4.1 A and 1.17 W/A, respectively. We present a visible up-conversion fiber laser pumped by using our developed high-power, high-efficiency 835-nm LD array.