Abstract

This paper presents modeling and analysis of light diffraction and light-intensity modulation performed by an optical phased array (OPA) system based on metal-coated silicon micromirrors. The models can be used in the design process of a microelectromechanical system (MEMS)-based OPA device to predict its optical performance in terms of its field of view, response, angular resolution, and long-range transmission. Numerical results are derived using an extended model for the 1st-order diffracted light intensity modulation due to phase shift. The estimations of the optical characteristics are utilized in the designs of an OPA system capable of active phase modulation and an OPA system capable of array pitch tuning. Both designs are realized using the Multi-User MEMS Processes (PolyMUMPs) in which polysilicon is used as structural material for the MEMS-actuated mirrors. The experiments are performed to evaluate the optical performance of the prototypes. The tests show that the individually actuated micromirrors, which act as phase shifters, can transmit the most optical power along the 1st-order diffracted beam by actively changing their out-of-plane positions. In addition, the 1st-order diffracted beam with high optical intensity can be steered for distance measurement.

Highlights

  • Photonic integrated circuit (PIC)-based optical phased array (OPA) systems generally consist of photonic components such as optical splitters, waveguides, couplers, antennas, and thermo-optic-tuning-based phase shifters on silicon chips [1,2]

  • Microelectromechanical system (MEMS)-based OPA systems [3] utilize silicon gratings or mirrors that can directly act as coherent emitters to obtain a relative phase difference of the pairing-diffracted light waves in the reflection mode

  • The microelectromechanical system (MEMS)-grating or micromirror-based OPA systems to control the phase of light leading are emerging as practical implementations for phased array beam steering

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Summary

Introduction

Photonic integrated circuit (PIC)-based optical phased array (OPA) systems generally consist of photonic components such as optical splitters, waveguides, couplers, antennas, and thermo-optic-tuning-based phase shifters on silicon chips [1,2]. Microelectromechanical system (MEMS)-based OPA systems [3] utilize silicon gratings or mirrors that can directly act as coherent emitters to obtain a relative phase difference of the pairing-diffracted light waves in the reflection mode. This leads to a relatively simple and straightforward design and construction of OPA systems. The MEMS-based OPA systems provide a relative phase shift in free space through their highly reflective elements, mitigating the temperature-gradient effects. The MEMS-grating or micromirror-based OPA systems to control the phase of light leading are emerging as practical implementations for phased array beam steering

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