A new SLM technology for fast achromatic and unpolarized wavefront correction

Spatial Light Modulators (SLM) are commonly used for wavefront correction or wavefront shaping. They feature unrivaled resolution (up to 3840x2160) in a compact form factor. But even if performances are regularly progressing, LCOS-SLM currently require a polarized light, have limited speed, diffraction effects and significant chromatic effects due to the phase wrapping required in most applications. This paper presents a completely different technology, intended to keep the SLM advantages but remove limitations listed above. This new device is based on the thermo-optical effect where the index of refraction is changed by a local temperature gradient. This physical effect is not sensitive to polarization, and the active material can be engineered to maximize the thermo-optical coefficient without degrading the optical performance such as transmission and chromatism. The device architecture and the design space are presented, and the results from the first prototypes are analyzed.