Complex wavefront engineering via decoupled space-time modulation

TL;DR

This paper introduces a hybrid wavefront engineering architecture that decouples electrical modulation from optical output, enabling high-speed, high-resolution, and large field-of-view spatial light modulation.

Contribution

The authors demonstrate a novel integration of metasurfaces with photonic circuits to overcome routing bottlenecks in SLMs, achieving independent control and reduced pixel pitch.

Findings

Achieved three-fold reduction in effective pixel pitch.

Demonstrated tunable varifocal lensing, beam steering, and holography.

Overcame physical routing constraints in dense pixel arrays.

Abstract

Solid-state Spatial Light Modulators (SLMs) are fundamentally limited in their ability to achieve high spatial complexity and high temporal bandwidth simultaneously. High-speed, low-energy modulation requires sub-wavelength active mode volumes, and sophisticated spatial wavefront engineering necessitates an ultra-fine pixel pitch. While small pixels can simultaneously solve both, in conventional architectures, the dense 2D electrical routing required for such pixels creates an insurmountable physical bottleneck. This results in a compromise between the SLM refresh rate, number of pixels and the field of view. Here, we demonstrate a hybrid architecture that overcomes this limit by spatially decoupling the electrical modulation plane from the optical output plane. By integrating a metasurface doublet with a photonic integrated circuit (PIC)-based optical phased array (OPA), we achieve independent 2D electrical control over each phase-element while simultaneously realizing a three-fold reduction in effective pixel pitch. This decoupling allows us to maintain the small active volume required for high-speed operation, while circumventing the routing constraints of dense spatial array of emitters. We utilize this platform to demonstrate tunable varifocal lensing, 2D beam steering, and 2D holography. Our work provides a scalable foundation for next-generation solid-state SLMs that simultaneously offer high speed, low power consumption, and large field of view.