PhD position on Experimental and theoretical investigation of low noise semiconductor lasers driven by intracavity nonlinearities

Since few years there is (and there will be) an increasing demand of high frequency and green electronics, covering a large variety of applications such as health care, defense, communications (satellites, 6G). To date, conventional electronics are reaching their limits, and are still limited to bulky and power consuming systems, whereas they could be replaced by less power consuming and fully integrated optical systems. This is one of the key point that has been recently pointed out by Europe and FRANCE2030 actions, through the national call PEPR Electronique (Programme et Equipements Prioritaires de Recherches). Accordingly, photonic integrated circuits (PIC) have to be developed, gathering all the necessary optical functions to go over electronics limitations, including compact and noiseless lasers, optical modulators and optoelectronic oscillators.

The main objective of this PhD project is to develop a 1550 nm VCSEL presenting an unprecedent low relative intensity noise, based on the insertion of optical non linearities (ONL) within the semiconductor microcavity. This approach has been proposed and experimentally demonstrated with success by Institut FOTON in glass and crystal doped solid-state lasers [1] leading to the development of a versatile and robust concept called "buffer reservoir". Indeed, by controlling the properties of the nonlinear process introduced in the laser, the noise reduction can reach up to 50 dB over several tens of GHz [2]. Such performances are by far unattainable by any other noise reduction approaches including optoelectronic electronic servo-locking. Nevertheless, the transition from long cavity solid state lasers to short semiconductor cavities such as a VCSEL will need additional refinements from both theoretical and experimental points of view to enable the buffer reservoir mechanism to be implemented during laser processing. Accordingly, the candidate will have to adapt buffer reservoir approach to semiconductor materials involved in both laser oscillation and noise reduction based on realistic inputs. Different ONL strategies (materials, doping, …) will be investigated and tested in order to fulfill the final device prerequisites. In addition, part of the thesis will focus on the possibility and relevance of actively controlling the physical properties involved in the buffer reservoir mechanism. To reach these objectives, the PhD candidate will benefit from Institut FOTON in house facilities (molecular beam epitaxy, cleanroom) [3], and from the >20 years long experience of Institut FOTON in modelling, designing, fabricating and characterizing lasers and more specifically InP based V(E)CSELs [4,5].