Tunable light sources lose their mirrors

A tunable infrared source that is ‘mirror-free’ and easy to align has been experimentally demonstrated for the first time and could result in a new source of light that is small, inexpensive and convenient to use.
Optical parametric oscillators (OPOs) are useful in the fields of spectroscopy, chemistry and other disciplines because they offer tunable coherent light – narrow-bandwidth light that has radiation with all the waves vibrating in phase – with wavelengths ranging from 2 to 10 micrometres, filling gaps that can’t be served by other sources. Unfortunately, conventional designs are hard to align and miniaturize as, apart from a nonlinear crystal, they also contain a pair of mirrors that need to be very precisely located. Although ‘mirrorless’ designs have been theoretically proposed in the past, an experimental prototype has not been demonstrated to date.
Carlota Canalias and Valdas Pasiskevicius have built a device that is highly compact, easy to align and has the ability to tune wavelengths with high precision in the near- and mid-infrared wavelengths. Their OPO relies solely on subtle modifications to the nonlinear crystal itself, rather than mirrors. The result is a new breed of OPO that consists of just the nonlinear crystal and a pump laser.
Author contact:
Carlota Canalias (Royal Institute of Technology, Stockholm, Sweden)
Tel: +46 855 378 159; E-mail: cc@laserphysics.kth.se