Generation of an ultrashort pulse train through ultrafast parity-time symmetry switching

We propose a scheme for the direct generation of an ultrashort pulse train as well as the further compression of pulsed lasers based on the nonlinearity inherent to parity-time (PT) symmetric optical systems. Implementation of optical parametric amplification in a directional coupler of & chi;(2) waveguides enables ultrafast gain switching through pump-controlled breaking of PT symmetry. We theoretically demonstrate that pumping such a PT symmetric optical system with a periodically amplitude-modulated laser enables periodic gain switching, which can directly convert a continuous-wave signal laser into a train of ultrashort pulses. We further demonstrate that by engineering the PT symmetry threshold, an apodized gain switching that enables the production of ultrashort pulses without side lobes. This work suggests a new approach for exploring the non-linearity inherent to various PT symmetric optical structures to extend optical manipulation capabilities. & COPY; 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

We propose a scheme based on nonlinearity of parity-time (PT) symmetric optical systems to directly generate an ultrashort pulse train and further compress pulsed lasers. By using optical parametric amplification in a directional coupler of & chi;(2) waveguides, ultrafast gain switching can be achieved through pump-controlled breaking of PT symmetry. Theoretical demonstrations show that periodically amplitude-modulated laser pumping of such a PT symmetric optical system enables periodic gain switching, converting a continuous-wave signal laser into an ultrashort pulse train. By engineering the PT symmetry threshold, apodized gain switching can produce ultrashort pulses without side lobes. This work suggests a new approach to explore the nonlinearity inherent to various PT symmetric optical structures and extend optical manipulation capabilities.