There is a need for high-power narrow-linewidth, small footprint, highly coherent diode lasers at various wavelengths (400-1800 nm) that can be utilized in many areas of photonics including fiber laser seeding, remote sensing, biomedical imaging, atomic clocks, quantum computing, THz spectroscopy, Raman spectroscopy, optical trapping, etc. Volume Bragg Grating (VBG) stabilized Fabry-Perot (FP) semiconductor lasers offer a versatile and robust platform for these applications. A Scanning Fabry-Perot Interferometer (FPI) is implemented for in-situ VBG alignment for these hybrid external cavity lasers (HECLs) in high volume production. Utilizing this method, it is possible to isolate a Single Longitudinal Mode (SLM) of a single spatial mode semiconductor laser with very narrow linewidth. The typical laser linewidth during the production process is measured to be 0.01 nm with an Optical Spectrum Analyzer (OSA) and a few MHz with the FPI, both of which were limited by the resolution of the instrument. However, the actual linewidth of these high-power lasers (up to 450 mW fiber-coupled and 600 mW free space) are measured in final testing using the heterodyne beat note method. These measurements show that these VBG-locked single spatial mode FP lasers have Lorentzian linewidth of less than 100 kHz. The result of narrower laser linewidth is achieved due to the effect on the external cavity feedback and the increased cavity length. The linewidths of these wavelength stabilized lasers between 633 nm and 1064 nm are presented here and the input of the isolator, laser driver electronics and temperature controller on linewidth are studied and discussed as a function of optical power, laser temperature, and wavelength.
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