The approach is said to have a fundamentally different principle to that of existing pulsed lasers, relying upon the coherent combination of multiple semiconductor lasers, each operating continuous-wave at different precisely defined frequencies. With precise control of each laser's amplitude and phase, the team says it is possible to produce complex pulsed optical waveforms with a degree of user flexibility.
The key to making the approach work is to phase-lock the semiconductor lasers to an optical frequency comb, which ensures the individual lasers have well-defined mutual coherence.
Many applications that require optical pulses typically need waveforms with a specific repetition rate, pulse duration and shape. Designing a laser to meet these parameters is challenging and, even when a suitable solution exists, size, complexity and ease of operation are further considerations.
Researcher David Wu said of the approach: "It consists of miniature and low cost semiconductor lasers that can all be integrated on the same chip, making our pulse generator potentially very compact, robust, energetically efficient and low-cost."
