Electron. Lett. 48, 867–869 (2012)

For swept source optical coherence tomography and high-speed transient spectroscopy, micro-electromechanical-systems-based vertical-cavity surface-emitting lasers (MEMS-VCSELs) are an appealing optical source owing to their narrow linewidth, continuous single-mode tuning and high-speed tunability. In particular, a wide tuning range (>100 nm) near 1,310 nm would be extremely useful for vascular and cancer imaging. Now, Vijaysekhar Jayaraman and colleagues in the USA have realized a MEMS-VCSEL that offers a continuous tuning range of 150 nm around a wavelength of 1,310 nm. The trick is to form a laser microcavity with a thin wide-gain-bandwidth InP-based multi-quantum-well active region and a wideband GaAs-based fully oxidized mirror. To enable the tuning, the researchers placed a suspended dielectric mirror on top of the cavity. When pumped at 980 nm through the suspended mirror, the MEMS-VCSEL emitted 1,310 nm light from the same side of the device. Applying a static voltage of around 56 V allowed for continuous tuning over a 150 nm span at a repetition rate of 500 kHz. The researchers say that the applications of this device can extend beyond swept source optical coherence tomography to transient spectroscopy for combustion monitoring and engine thermometry.