Narrowband, high power light from diode lasers

We have used a 100-mW cw laser diode array to amplify the light from a low power, single stripe diode laser (both lasers commercially available). The input light was spectrally narrowed and frequency stabilized to <300 kHz using optical feedback from a Fabry-Perot cavity, and the amplified beam had the same spectral characteristics. Also, the ~90-mW amplified beam had a single diffraction-limited spatial mode corresponding to the full 100-microm width of the array, indicating that all its stripes were coherent. When viewing the output of the free-running laser array, we observe that the input light causes its output spectrum and spatial distribution to be dramatically narrowed. We have tested a simple quantitative model of this process.