High-Speed Multimode Fiber Imaging Using Binary-Modulated Silicon Photonics Optical Phased Array

Abstract

Multimode fiber (MMF) imaging is a powerful technique for minimally invasive endoscopy. However, the absence of high-speed spatial light modulators (SLMs) poses a challenge in the pursuit of high-speed, real-time MMF imaging. Silicon optical phased array (OPA) serves as a possible solution to high-speed mode field manipulation; however, the nonlinearity in the phase response of silicon p-i-n diodes makes it unfeasible to realize precise multilevel control at a high speed. In this paper, it is shown that the driving scheme of p-i-n diodes in a silicon OPA can be simplified by using binary modulation, enabling the use of high-speed digital voltage drivers instead of high-precision digital-to-analog converters. The OPA achieves modulation at 1 MHz, which is three times faster than state-of-the-art SLMs. Experimental results demonstrate a frame rate of up to 500 frames per second. The image-reconstruction period is as short as 0.1 ms per frame, making the system suitable for real-time imaging. The measured spatial resolution is 2.3 µm with a field of view diameter of 105 µm, which approaches the diffraction limit.