High-power indium gallium arsenic phosphide-active diode lasers at lambda = 808 nm.

摘要

808-nm diode lasers have attracted particular attention due to their ability to efficiently pump Nd:YAG solid-state lasers. Although the pumping efficiency greatly exceeds that of a Xe flashlamp, high-power operation has been limited. The difficulty lies in the fact that to reach such a short wavelength, aluminum must be added to the active region. AlGaAs-active diode lasers not only suffer poor high-power reliability but posses unusually steep degradation rates as well as a propensity for sudden failures. We shall review the material alternatives for 808-nm diode lasers, presenting evidence that leads us to conclude that InGaAsP-active devices offer the best opportunity for high-power reliability. Previous studies failed to fully exploit their advantages, due to a common misconception. We break the "myth", that any aluminum compounds adversely affect reliability, by exploring structures with high band-gap materials as cladding and confining layers. Devices constructed from said epi-structures allow us for the first time to determine the internal power density at which catastrophic optic mirror damage occurs, P¯ COMD ∼18 MW/cm2, twice that for AlGaAs-active devices and the same as that for InGaAs-active devices. Therefore, we infer that 808-nm InGaAsP-active devices will operate reliably at powers 2--3 times that of devices with AlGaAs active regions, P = 40--60 W from 1-cm long bars. We conclude by utilizing a novel mode discrimination technique that enables 808-nm devices to achieve a power of P = 8.8 W from the fundamental (transverse) mode.