Tunable high-power blue external cavity semiconductor laser

•A high-power blue Littrow-type external cavity laser is realized.•The laser with grating lines parallel to the p-n junction has good performance.•The spectra, power, and wavelength tuning range are investigated in detail. A commercially available high-power GaN-based blue laser diode has been operated in a simple Littrow-type external cavity (EC). Two kinds of EC configurations with the grating lines perpendicular (A configuration) and parallel (B configuration) to the p-n junction are evaluated. Good performance has been demonstrated for the EC laser with B configuration due to the better mode selection effect induced by the narrow feedback wavelength range from the grating. Under an injection current of 1100mA, the spectral linewidth is narrowed significantly down to ∼0.1nm from ∼1nm (the free-running width), with a good wavelength-locking behavior and a higher than 35dB-amplified spontaneous emission suppression ratio. Moreover, a tuning bandwidth of 3.6nm from 443.9nm to 447.5nm is realized with output power of 1.24W and EC coupling efficiency of 80% at the central wavelength. The grating-coupled blue EC laser with narrow spectral linewidth, flexible wavelength tunability, and high output power shows potential applications in atom cooling and trapping, high-resolution spectroscopy, second harmonic generation, and high-capacity holographic data storage.