Widely Tunable Micro-Mechanical External-Cavity Diode Laser Emitting Around 2.1 $\Mu$m

A widely tunable (Delta lambda/lambda = 7%) micro-mechanical external cavity GaSb-based diode laser (mu ECL) emitting around 2.1 mu m is presented. A micro-machined grating with a rectangular grating profile, which can be tilted electrostatically, is employed as wavelength selective element within the external cavity using a Littrow configuration. An optimized grating profile leads to a high diffraction efficiency in the -1st diffraction order and therefore to a broad tuning range of 152 nm. The maximum output power of the fiber coupled mu ECL system varied only moderately between 22 and 10 mW across the tuning range.