Last year, Laser Focus World reported on a microelectromechanical systems (MEMS)-based 1310 nm widely tunable vertical-cavity surface-emitting laser (VCSEL) from Praevium Research (Santa Barbara, CA), Thorlabs (Newton, NJ), Advanced Optical Microsystems (AOMicro; Mountain View, CA), and the Massachusetts Institute of Technology (MIT; Cambridge, MA) that enabled 760 kHz optical coherence tomography (OCT) scanning in conjunction with a 110 nm tuning range. A year later, the same research group has reached new heights with a 150 nm tuning range at 1310 nm—the widest tuning range reported for any VCSEL at any wavelength.
The record tuning range was made possible through an improved cavity and electrostatic actuator design. These MEMS-based VCSELS essentially consist of a lasing cavity in which the top mirror is suspended on a MEMS actuator. Tunability was expanded by using a thinner cavity in an optically pumped configuration. Optical pumping eliminates resistive heating and the need to dope the mirrors and cavity, significantly reducing free-carrier absorption and subsequently reducing threshold gain for lasing over a wider portion of the gain spectrum. The new devices use a shorter total cavity length that extends the free-spectral range. Wideband mirrors and wider-gain indium-phosphide (InP)-based quantum wells also promote an expanded tuning range. Contact Vijaysekhar Jayaraman at [email protected].
Gail Overton | Senior Editor (2004-2020)
Gail has more than 30 years of engineering, marketing, product management, and editorial experience in the photonics and optical communications industry. Before joining the staff at Laser Focus World in 2004, she held many product management and product marketing roles in the fiber-optics industry, most notably at Hughes (El Segundo, CA), GTE Labs (Waltham, MA), Corning (Corning, NY), Photon Kinetics (Beaverton, OR), and Newport Corporation (Irvine, CA). During her marketing career, Gail published articles in WDM Solutions and Sensors magazine and traveled internationally to conduct product and sales training. Gail received her BS degree in physics, with an emphasis in optics, from San Diego State University in San Diego, CA in May 1986.