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.