Chip-based nonmechanical beam steerer in the midwave infrared

Abstract

Midwave infrared (MWIR) light is critically important for a variety of applications, such as chemical sensing and LIDAR. Directional control over MWIR light is required for these applications and is typically accomplished using mechanical devices such as gimbal-mounted mirrors. Mechanical steerers, however, are subject to a host of problems, and replacing them has been a long-standing goal. In this paper, we describe the first nonmechanical beam steerer capable of continuous angular tuning in the MWIR. These devices are chip-based and provide steering in two dimensions without relying on moving parts. Previous work has demonstrated nonmechanical beam steering (NMBS) in the short-wave infrared and near infrared using a waveguide in which a portion of the propagating light is evanescently coupled to a liquid crystal (LC) layer in which the refractive index is voltage-tuned. We have extended this NMBS technology into the MWIR by utilizing a unique combination of materials, specifically chalcogenide glass waveguides and LC materials that exhibit high MWIR transparency. We explain the working principles behind these steerers, discuss material considerations for transparency in the MWIR, describe steerer fabrication, and present experimental results showing up to 14° in-plane and 0.6° out-of-plane steering.