High-performance optical beam steering with nanophotonics

Sam Lin,Yixin Chen,Zi Jing Wong

doi:10.1515/nanoph-2021-0805

Abstract

Abstract The ability to control and steer optical beams is critical for emerging technologies. Among these are light detection and ranging (LiDAR), laser display, free space communication, and single pixel imaging. Improvements in these areas promise enhanced 3D data collection capabilities, orders of magnitude increase in wireless data rate, less expensive cameras, and ever more immersive virtual/augmented reality (VR/AR) consumer electronics. Bulk mechanical or liquid crystal devices are conventionally utilized platforms that achieve optical beam steering, but they are bulky and limited in speed and reliability. Instead, chip-scale photonic platforms offer faster and more elegant mechanisms to manipulate light, capable of minimizing device size, weight, and power. Additionally, a critical device metric is its far field resolution, which influences fine feature detection in imaging applications, laser display quality, and signal power and fidelity of free space communication links. Strong light matter interaction achieved with nanophotonic approaches generally makes devices smaller and more efficient, yet ultimately these effects must be scaled to suitable aperture sizes to maintain good resolution. Recent years have seen rapid development in these performance characteristics, spurred by research on active metasurfaces, slow light waveguides, and waveguide phased arrays, with different architectures encountering unique tradeoffs between device complexity, resolution, and speed, in attempting to achieve groundbreaking values for all three. We review these diverse emerging nanophotonic approaches that aspire to achieve high-performance optical beam steering.

Highlights

Changing the direction of light at high speed is an objective important for a myriad of applications [1, 2]
Free space telecommunication would be boosted by the high carrier frequency of near infrared (NIR) light, enabling data rates as high as those supported by optical fibers, and benefit from well directed signal intensity [6]
The array size is fixed for architectures like active metasurfaces (Figure 1A) and integrated optical phased arrays along the array dimension (Figure 1C), while grating-like devices (Figure 1B), with optical power coupled from an in-plane source, have a near field profile characterized by exponential decay in Cn along one spatial direction

Summary

Introduction

Changing the direction of light at high speed is an objective important for a myriad of applications [1, 2]. Display technologies that currently rely on mirrors that flip back and forth could become even more portable, robust, and bright, and operate at a higher frame rate Common to all these technologies are the requirement for high speed, high resolution, and minimized device size, weight, and power. Bulk mechanical systems are constrained by their size, and as a result speed, and typical response times for liquid crystals are only on the order of milliseconds [10, 13]. Alongside these have developed other more exotic methods for beam steering. S. Lin et al.: High-performance optical beam steering with nanophotonics way to deflect light at high speed [16, 17], albeit with low modulation efficiency. We summarize with an outlook for active beam steering in general, evaluate the prospects of each device class, and overview the necessary breakthroughs required for their commercialization

Performance parameters for active beam steering

Active phase gradient metasurfaces

Slow light beam scanning

Optical phased arrays

Findings

Summary and outlook