Grant: Discovery Grants Program - Individual

My research program consists in developing nanostructured materials with unusual optical properties and using them in lasers to enhance laser emission properties, such as brightness and adjustable emission spectrum. Two approaches are used for the fabrication of these nanostructured materials. We use Glancing Angle Deposition (GLAD) to deposit thin films of nanoporous composite materials with anisotropic effective optical properties onto a laser mirror. We also use nanofabrication technologies to corrugate the top layer of a laser mirror to confer suitable optical properties to the mirror at normal incidence. Anisotropic mirrors used in the laser resonators have enabled a compact single mode microchip laser device at high power. Such a compact laser could find applications in lidars for autonomous navigation, such as for self-driving vehicles or airborne devices like drones. Lidars are a key component to achieve real-time mapping of the scene surrounding a vehicle. However, the limited brightness in other existing designs adversely impacts the range and recording speed in real time. Our research will address this issue by seeking frequency-agile, single-mode laser sources at higher power that retain the miniature and monolithic quality of current laser designs. To achieve that goal, my research program also aims at achieving dynamical control of the optical response of our laser mirrors. We will incorporate into our multilayer design thin films of phase change materials, which can undergo a large change of refractive index by heating or by shining a light pulse on them, or electro-optic materials, whose refractive index can be controlled with an applied voltage bias. This will allow for the adjustment of the optical response of the laser mirrors in real time. A crucial enabling feature of our laser design containing nanostructured thin films is the possibility of making the two polarization states coalesce into a single state by adjusting the resonator at a special operation point called an exceptional point (EP). EPs have a very interesting property, whose potential has not fully been studied yet: the extremely rapid change in the polarization state characteristics of the emitted beam at an EP as a function of a perturbation. Hence, a large variation of such characteristics should occur from tiny variations in the characteristics of the laser mirrors. In addition, if the top layer that makes up a laser mirror is nanoporous, we expect such mirrors to have optical properties that strongly depend on the surrounding chemical environment. We will thus study the synergic effect of operating a laser at an EP that contains a nanoporous GLAD-made film, for sensing applications. This research program will train students in theoretical and experimental, as well as fundamental and applied aspects at the interface between materials science and photonics.