InGaAsP/InP diode laser pumping sources for eye-safe solid-state and fiber lasers

Record high power InP-based diode laser pumps operating at 1450 nm and 1850 nm have been fabricated and tested. Single-element 100 mum stripe lasers and 1 cm long arrays (both with cavity length of 2-2.5 mm) are appropriate for fiber and bulk solid-state laser pumping, respectively. The differential quantum efficiency for 1450 nm lasers was 55% and 47% for 1850 nm emitters. The maximum CW output powers for 1 cm diode arrays are 42 W for 1450 nm and 14 W for 1850 nm wavelength ranges. The output photon flow (per facet) at maximum current for 1450 nm sources is 40% higher than that for commercial GaAs-based emitters, while for 1850 nm sources it is 50 % lower. A simple estimation shows that the parameters achieved for 1450 nm diode lasers could provide overall efficiency for an 1640 nm Er3+ :YAG laser with InP-based pumping comparable with that of a GaAs laser pumped Er3+:YAG laser. More importantly, the expected active media overheating in the case of InP-based pumping is lower by an order of magnitude compared to a GaAs laser pumped Er3+ :YAG laser. Data on the lifetime for InP-based diode arrays confirm that high reliability is an additional advantage of long wavelength pumps compared to traditional GaAs-based pumps.