Microwave photonics. Optical control of electronic functions

One of the challenges facing future electronic systems, and in particular microwave systems, is their ability to adapt to extremely dense and evolving spectral environments. This adaptability translates either into the ability to process signals with increasingly wide bandwidths, or into the ability to reconfigure very rapidly to adapt its operating frequency band to the spectral environment. These ultra-rapid reconfiguration capabilities involve the notion of microwave routing or switching. The most promising approach to controlling these devices with a high degree of temporal precision is to use an optical pulse, which has the dual advantage of electromagnetic immunity and temporal jitter on the order of femtoseconds. It is therefore necessary to master the interactions between a light wave and a material. Due to the fundamentally different nature of existing materials (insulator, conductor, semiconductor), interactions of different kinds can occur with these materials when they are subjected to a flow of photons in a wavelength range from X-rays to the far infrared. These interactions can be transcribed through various modifications to the propagation of the incident electromagnetic wave, which will be reflected, absorbed or refracted by this material.

The aim of this article is to describe the interactions of a light wave with semiconductor materials, and then to identify new optically controllable microwave functions. The first paragraph is devoted to the main light/matter interactions, followed by a paragraph on light emission and absorption mechanisms in semiconductor materials. The third paragraph deals with the photoconductivity of semiconductor materials. Finally, the following paragraphs cover the field of new optically controlled microwave functions, in particular photomixing and microwave signal sampling.