Nonlinear Dynamics in Semiconductor Lasers 2023 - Abstract
Virte, Martin
Multimode emission in a semiconductor laser is typically seen as a negative feature. Although it is sometimes an acceptable drawback for instance when high powers are required, low-linewidth single mode emission remains widely preferred for most applications. From a nonlinear dynamics viewpoint, a multimode laser is a significantly more complex system due to the intrinsic coupling and competition between modes. The underlying mechanisms leading to coupling between laser modes are relatively well-known, but a clear quantification of the process is still missing, and direct measurements are out of reach. Taking the problem in reverse, we explore how the dynamics of multi-wavelength lasers - i.e. multimode lasers with a few modes emitting in a controlled way - could be harnessed for application. We consider here their potential to perform all-optical wavelength conversion. In practice, by taking advantage of the progress of generic photonic integration technology, we can relatively easily design custom devices emitting at different wavelengths and including some modal control mechanisms. Subjecting these devices to modulated optical injection makes an excellent testbed to investigate the nonlinear behavior of multi-wavelength lasers, especially to analyze how well they can convert a given optical signal to another wavelength. We show here that multi-wavelength lasers can very efficiently replicate narrowband optical frequency combs at other wavelengths while preserving phase-locking between comb lines. Moreover, phase-locking between different wavelengths can also be achieved and cascaded, thus opening the way to significant comb expansion. In addition, we show that conversion of data signals is also possible.