ET-SLM neurons · Electrothermal Spatial Light modulator for neuronal tissue imaging in depth

In the current era of images, spatial light modulators (SLM) are essential building blocks to improve the performance of new photonic devices, all the way from the consumer market, with displays and cameras, to the research and clinic environments with advanced microscopy. However, spatial-light modulation that is capable of generating sub-millisecond phase-shifts without artifacts and polarization dependence is challenging. The ET-SLM neurons project leverages on a concept based on an electro-thermo-optical effect recently introduced by the host laboratory (Institut de la Vision, Paris) in collaboration with the Quidant lab (ETH Zurich), and on a set of innovative know-hows of temporal pulse-shaping and thermal properties engineering developed by the fellow. The proposed approach relies on the temperature dependence of the refractive index of materials (physical effect involved in mirages). By engineering the temperature landscape in a thermo-optical material, one forms a distribution of refractive index associated with a desired optical function like a lens or a more complex free-form element (Nat. Photonics, 2019). However, this concept, coined as Smartlens, is still in its infancy, with limitations in terms of response time and heat confinement. Those problems have been recently overcome by the fellow (Nat. Communication, 2021), taking advantage of the transient heat state and using heat sink. The project aims at combining these innovations by first developing a tunable multiplane focusing and imaging system for microscopy, and applying it to monitor neuronal activities in 3D. Its validation will pave the way to developing an Electrothermal (ET) SLM featuring a sub s response time. Such performances would particularly improve the domain of wavefront shaping to image through dynamic scattering media such as in-vivo brain cells. In this context, we aim to combine the use of the ET-SLM with advanced microscopy systems to perform in-depth, live neuronal imaging.