While lasers are now essential in numerous industrial fields from telecommunication to sensing, many applications require the simultaneous or sequential use of different wavelengths. This imposed the use of either many different lasers or so-called “tunable” lasers. The former requires optical switches, robust micrometer precision of several optical elements, simultaneous control and monitoring of several lasers, thus leading to bulky and complex systems. On the other hand, tunable lasers only emit a single wavelength at once, tuning is slow (several microseconds or longer) and can require complex commands.
Multi-wavelength lasers – devices having the capability to selectively emit at different wavelengths – have been proposed but the lack of an efficient and precise control mechanism made them unsuitable.
The VUB Brussels Photonics Team B-PHOT, in collaboration with the Institute for Applied Physics of the Technical University Darmstadt, has developed a wavelength control system for multi-wavelength lasers to combine the best of both worlds. The all-optical control loop is monolithically integrated with the laser and gives precise control over the multi-wavelength emission through a single control voltage parameter. It allows to precisely balance the different emission wavelength – e.g. to reliably obtain equal output power at different wavelengths – or quickly switch between wavelengths at the nanosecond timescale. The control system is compatible with generic platforms and mass manufacturable.