InterScience has developed a digitally tunable diode laser that has the capability to emit one or more wavelengths in any desired order and/or simultaneous selection of more than one wavelength. Unlike conventional external cavity tunable diode lasers that depend on mechanical means to scan the laser's wavelength range sequentially from one end to the other, the DTDL employs a micromirror array to switch among any wavelengths within the laser's emission spectrum, in any sequence in microseconds. The device has immediate applications in optical and infrared laser spectroscopy for chemical sensing, pollution control and biomedical applications, as well as wavelength division multiplexing (WDM) for optical communications.