Shot-noise limited, 10 MHz swept-source optical coherence tomography for retinal imaging

TL;DR

This paper presents a low-noise, 10 MHz swept-source optical coherence tomography system operating at 1050 nm, enabling high-speed, high-sensitivity retinal imaging close to the shot noise limit.

Contribution

The authors develop a novel low-noise, high-speed swept-source OCT using all-normal dispersion supercontinuum and a long chirped fiber Bragg grating, expanding biomedical imaging capabilities.

Findings

Achieved 10 MHz sweep rate with low noise at 1050 nm

Demonstrated retinal imaging with 84 dB sensitivity

Approached shot noise limit in sensitivity

Abstract

Akinetic swept-sources are essential for high-speed optical coherence tomography (OCT) imaging. Time-stretched supercontinuum (TSSC) lasers have proven to be efficient for multi-MHz swept-sources. However, lack of low-noise broadband lasers and of large dispersion devices in the water low-absorption band at 1060 nm have limited the biomedical applications of TSSC lasers. In this letter, an approach to tune the wavelength around 1050 nm over 90 nm with low-noise at 10 MHz is presented. This is based on all-normal dispersion (ANDi) supercontinuum dynamics, and employs a long chirped fiber Bragg grating (CFBG) to time-stretch a broadband pulse with a duty cycle of 93 %. Retinal images are demonstrated, with a sensitivity of 84 dB - approaching the shot noise limit. We believe this high-speed low-noise swept-source will greatly promote the development of OCT techniques for biomedical applications.