Low-noise fiber femtosecond laser with cascade acoustic-optical pulse picker for time-resolved imaging

Abstract

Fiber mode-locked lasers are widely used in time-resolved imaging, but at repetition rates in the hundred kHz range, amplified spontaneous emission (ASE) poses a major concern. To address this problem, this paper presents a straightforward approach to achieving a low repetition rate and low noise fiber femtosecond laser. A cascade acoustic optical pulse picker is employed to effectively suppress ASE noise, resulting in an achieved maximum signal-to-noise ratio of 45 at a repetition rate of 50 kHz. The amplification property of the Er-doped fiber amplification is precisely presented by measuring pulse energy at different repetition rates. The potential for time-resolved imaging is demonstrated with high confidence through single pulse interferometry modulated by electro-optic modulation, which exhibits low ASE levels, and ultrafast imaging using the multiple exposure imaging system, which reveals sufficient light intensity levels.