Light and Microwaves in Laser Frequency Combs: An Interplay of Spatiotemporal Phenomena

Interference of laser beams in a suitable medium creates dynamic optical gratings, which can serve for a wide variety of applications, ranging from real-time holography to ultrasound generation. Typically, the interference occurs in a sample material that is separated from the laser sources. Here, we explore a new aspect of laser-induced dynamic gratings: microwave generation occurring inside the cavity of semiconductor laser frequency comb generators, such as quantum cascade lasers and interband cascade lasers. The interplay between laser light and microwaves in these devices reveals intracavity spatiotemporal phenomena that are of great importance for the understanding of their physics and for their operation to be efficient. Grating effects related to laser locking dynamics, structured cavities, and microwave propagation are demonstrated. Applications in science and technology based on these phenomena, including the realization of novel hybrid electronic-photonic devices, will also be presented.