5 W continuous wave power, 0.81-μm-emitting, Al-free active-region diode lasers

High power, 0.81-μm-emitting, semiconductor diode lasers are used as pump sources for Nd:YAG solid-state lasers. Devices (1-mm-long) consisting of a $\mathrm{InGaAsP/}$ ${\mathrm{In}}_{\mathrm{0.5}}{\mathrm{(Ga}}_{\mathrm{0.9}}{\mathrm{Al}}_{\mathrm{0.1}}{\mathrm{)}}_{\mathrm{0.5}}\mathrm{P/}$ ${\mathrm{In}}_{\text{0.5}}({\mathrm{Ga}}_{\text{0.5}}{\mathrm{Al}}_{\text{0.5}}{)}_{\text{0.5}}\mathrm{P}$ laser structure provide a threshold-current density, $J_{\mathrm{th}},$ of $\text{290\hspace{0.17em}}{\mathrm{A/cm}}^{\mathrm{2}}$ and a relatively high threshold-current characteristic temperature, $T_0$ (140 K). Uncoated diode lasers (1.2-mm-long) have a maximum continuous wave output power of 5 W (both facets) at 20 °C. The internal power density at catastrophic optical mirror damage (COMD), ${\mathrm{P̄}}_{\mathrm{COMD}},$ is determined to be $\text{9.1\hspace{0.17em}}{\mathrm{MW/cm}}^{\mathrm{2}};$ that is, 1.8 times that for GaAs-active layer, Al-free, uncoated devices. Coated, InGaAsP-active devices are expected to have ${\mathrm{P̄}}_{\mathrm{COMD}}\text{=18\hspace{0.17em}}{\mathrm{MW/cm}}^{\mathrm{2}},$ more than twice the ${\mathrm{P̄}}_{\mathrm{COMD}}$ of AlGaAs-active, 0.81-μm-emitting devices with the same emitting aperture. Therefore, 0.81-μm-emitting, InGaAsP-active diode lasers should operate reliably at powers at least twice those of AlGaAs-based devices with the same contact-stripe geometry.