Scientists make breakthrough in pulsed laser design

Scientists from the University of Southampton have developed a technique to create high power pulsed lasers used in telecommunications and metrology which are potentially more energy efficient.

The new method developed by researchers from the University’s Optoelectronics Research Centre (ORC) works on a fundamentally different principle to existing pulsed lasers.

Any application that requires optical pulses typically needs waveforms of a specific repetition rate, pulse duration, and pulse shape. This puts exacting parameters on the laser design.

The technique developed at Southampton relies upon the coherent combination of multiple semiconductor lasers, each operating continuous-wave at different precisely defined frequencies (wavelengths).

The team phase-locked the semiconductor lasers to an optical frequency comb, which ensures the individual lasers have well-defined mutual coherence.

This controls the amplitude and phase of each laser’s output, making it possible to produce complex pulsed optical waveforms.

David Wu, lead author of the study said: “As our new technique is based on a different approach to that currently used, it has several distinct features that are relevant in many applications. First, it is easily scalable – by combining a larger number of input lasers, shorter or more complicated-shape pulses and/or more power can be obtained. It can also generate pulses with a very low-level of noise (down to the quantum limit) and very high (greater than one THz) repetition frequencies.

“Finally, it consists of miniature and low-cost semiconductor lasers that can be all integrated on the same chip, making our pulse generator potentially very compact, robust, energetically efficient, and low-cost.”

It is believed that the concept and phase-locking technology developed could be widely applicable with the broader optics/photonics community.

The research is reported in a recent issue of the journal Optica – a new The Optical Society (OSA) journal, which focuses on rapid dissemination of high-impact results in all areas of optics and photonics.

The research is funded by the EPSRC through the Early Career Research Fellowship of Dr Slavik (EP/K003038/1) and through the “Photonic Hyperhighway” Programme Grant (EP/101196X).

Richard Wilson

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