SLM-Based Optical Computing Platform for Designing Polychromatic Flat Optics

Polymer-based diffractive flat optics modulate the optical functions of their refractive counterparts using an equivalent surface relief phase profile [1]. For multiwavelength operation, the diffractive phase profile must be parametrically optimized to find a suitable solution that ensures high polychromatic performance taking into consideration both material and fabrication constraints [2], [3]. Typical forward and inverse design methods require reliable physical optical models whose computational costs increase with the number of operating wavelengths [4]. We present a novel optical computing platform to accelerate the optimization of diffractive optics design by performing the free space propagation step in hardware. We employ a filtered supercontinuum laser source, a spatial light modulator (SLM), and a camera detector on a movable stage, to iteratively evaluate and optimize the surface relief profile of real microstructured diffractive optical devices for imaging in the visible spectrum. The equivalent single and multi-order phase delay through the microstructure profile is reproduced on the SLM for each wavelength (λ=[450, 550, 650] nm), compensating for the dispersion of the real material and the SLM phase calibration.