A wavelength-selectable laser device (302, 502), comprising: an array of laser emitters (310-1 to 310-n, 510-1 to 510-n), each of the laser emitters (310-1 to 310-n, 510-1 to 510-n) including a gain region for emitting light across a range of wavelengths including a plurality of channel wavelengths and a back reflector (314, 514) for reflecting light from the laser emitters (310-1 to 310-n, 510-1 to 510-n); and a filtered external cavity (320, 520) coupled to the laser emitters (310-1 to 310-n, 510-1 to 510-n), the filtered external cavity (320, 520) being configured to filter light received from respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) at different respective channel wavelengths for the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and configured to reflect at least a portion of the light at the respective channel wavelengths back to the gain region in the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) such that a lasing cavity is formed with the filtered external cavity (320, 520) and at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n) of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and lasing occurs at respective at least one selected channel wavelength and/or wavelengths reflected back to the gain region of the at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n); wherein the filtered external cavity (320, 520) comprises: a dispersive optical element configured to receive light from the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) at different angles and configured to reflect or pass different channel wavelengths of the light at different angles; and a front reflector configured to receive a different channel wavelength passed or reflected by the dispersive optical element for each of the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and configured to reflect the different channel wavelengths, respectively, back to the gain region in the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) such that the lasing cavity is formed between the front reflector and the back reflector (314, 514) of the at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n); whereby each of the laser emitters (310-1 to 310-n, 510-1 to 510-n) emits light across a range of wavelengths including the channel wavelengths. an array of laser emitters (310-1 to 310-n, 510-1 to 510-n), each of the laser emitters (310-1 to 310-n, 510-1 to 510-n) including a gain region for emitting light across a range of wavelengths including a plurality of channel wavelengths and a back reflector (314, 514) for reflecting light from the laser emitters (310-1 to 310-n, 510-1 to 510-n); and a filtered external cavity (320, 520) coupled to the laser emitters (310-1 to 310-n, 510-1 to 510-n), the filtered external cavity (320, 520) being configured to filter light received from respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) at different respective channel wavelengths for the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and configured to reflect at least a portion of the light at the respective channel wavelengths back to the gain region in the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) such that a lasing cavity is formed with the filtered external cavity (320, 520) and at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n) of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and lasing occurs at respective at least one selected channel wavelength and/or wavelengths reflected back to the gain region of the at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n); wherein the filtered external cavity (320, 520) comprises: a dispersive optical element configured to receive light from the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) at different angles and configured to reflect or pass different channel wavelengths of the light at different angles; and a front reflector configured to receive a different channel wavelength passed or reflected by the dispersive optical element for each of the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and configured to reflect the different channel wavelengths, respectively, back to the gain region in the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) such that the lasing cavity is formed between the front reflector and the back reflector (314, 514) of the at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n); a dispersive optical element configured to receive light from the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) at different angles and configured to reflect or pass different channel wavelengths of the light at different angles; and a front reflector configured to receive a different channel wavelength passed or reflected by the dispersive optical element for each of the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) and configured to reflect the different channel wavelengths, respectively, back to the gain region in the respective ones of the laser emitters (310-1 to 310-n, 510-1 to 510-n) such that the lasing cavity is formed between the front reflector and the back reflector (314, 514) of the at least one selected laser emitter (310-1 to 310-n, 510-1 to 510-n); whereby each of the laser emitters (310-1 to 310-n, 510-1 to 510-n) emits light across a range of wavelengths including the channel wavelengths.