ABSTRACT
There is an increasing demand for semiconductor diode lasers with emission wavelengths in the 0.70-1.0 /zm range which can operate reliably at high output power levels. Large aperture, high-output-power, spatially incoherent diode lasers are required for a variety of applications including pumps for solid-state lasers and sources for new medical therapies (including Photo dynamic therapy for cancer [1], PDT, and Magnetic Resonance Imaging, MRI, using laser polarized gases [2]). On the other hand, spatially coherent, single-mode devices, are needed for applications such as optical recording, high-speed, high-resolution printing, parallel optical signal processing, and as pump sources for rare-earth doped fiber or waveguide amplifiers. Until recently, the workhorse material for these types of device structures has been AlGaAs deposited on GaAs substrates, due primarily to the ease of growing nominally lattice-matched structures throughout the entire alloy composition range. Extending the emission wavelength range longer than A. = 0.87 fim, requires the use of a compressively strained InGaAs quantum well active region.
