Microelectromechanical wavelength-tunable vertical cavity laser

Wavelength-tunable semiconductor diode lasers have potential applications ranging from wavelength division multiplexed optical communications and interconnects to spectroscopic remote sensing. A wide and continuous tuning range is desirable in many of these applications; however, monolithically-fabricated devices, which are tuned by refractive index effects, have been limited to a fractional tuning range of 1% at most. Tuning based on micromechanical modulation of the physical cavity length faces no such limitation, and is especially suitable for the short cavity lengths in vertical-cavity surface-emitting lasers (VCSELs). Recently we demonstrated a tunable resonant-cavity light emitter based on the micromechanical motion of a suspended gold/silicon nitride top mirror, and achieved pulsed laser oscillation in a similar device. Here we describe continuous-wave operation of a VCSEL operating in a single longitudinal and transverse mode and continuously tunable over 18 nm.