The Adoption of Chalcogenide Glass Fiber as Pulse Stretcher in an All-Fiber Structured 2 μm Chirped Pulse Amplification System

Weiwang Zhang,Juan Wang,Hongfei Ren,Changjun Quan,Qiuhua Nie,Peilong Yang,Bin Yan,Peipeng Xu,Yingying Wang,Miao Qiu,Shaohui Mo,Shixun Dai,Junwei Zhu,Xing Li,Shengchuang Bai,Feifei Chen,Ruwei Zhao

doi:10.1109/jphot.2021.3061548

Abstract

We present the development of an As 2 S 3 fiber-based reusable inline optical connector; and, for the first time to the best of our knowledge, integrated it into a 2 μm chirped pulse amplification system as the pulse stretcher. By this mechanism, a near 20 times pulse stretching ratio was achieved in 0.5 m-long this As 2 S 3 fiber and the introduction of insertion loss as low as 2.84 dB while it was connected with silica fiber. After the follow-up fiber amplification and self-compression mechanism, the laser average output power was boosted to 1.97 W and pulse duration was optimized to 2.53 ps. Moreover, to further inspect the laser pulse property, the pulses were then delivered into a 5.3 m-long ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN) fiber which was fusion spliced to SM1950 fiber. Thanks to the 0.4-dB low fusion splice loss between these fibers, a 1.56-W supercontinuum source with bandwidth of 1.93-3.50 μm is obtained. The measured two hours of root-mean-square value of power fluctuation of this laser source is 0.13%, indicating an ultra-high long-term power stability. This work will lay a solid foundation in the realization of the all-fiber structured high-power thulium-doped fiber amplifier with high compactness.

Highlights

All-fiber 2 μm ultrashort pulsed laser sources with good beam quality and high stability have attracted much attentions owed to their potential applications in such fields as optical frequency combVol 13, No 2, April 2021[1], [2], multi-modal imaging [3], [4], cascaded Raman laser realization [5], [6], and mid-infrared supercontinuum (Mid-IR SC) generation in soft-glass fibers [7], [8]
We present the development of an As2S3 fiber-based reusable inline optical connector; and, for the first time to the best of our knowledge, integrated it into a 2 μm chirped pulse amplification system as the pulse stretcher
We demonstrated the high-quality As2S3 fiber connector fabrication and for the first time used it in an all-fiber structured watt-level 2 μm pulsed laser CPA system as the pulse stretcher, which showed great advantages in both insertion loss and pulse stretching ratio

Summary

Introduction

All-fiber 2 μm ultrashort pulsed laser sources with good beam quality and high stability have attracted much attentions owed to their potential applications in such fields as optical frequency combVol 13, No 2, April 2021[1], [2], multi-modal imaging [3], [4], cascaded Raman laser realization [5], [6], and mid-infrared supercontinuum (Mid-IR SC) generation in soft-glass fibers [7], [8]. Two approaches, direct mode-locking [9]–[11] and Raman soliton self-frequency shift (SSFS) [12]–[18], are usually used to realize all-fiber 2 μm femtosecond sources. Compared with direct mode locking, SSFS enabled 2 μm sources in silica fiber pumped by 1.55 μm Er-doped femtosecond fiber laser is more advantageous in terms of long-term stability, signal-to-noise ratio (SNR), compactness and costs. A. Rezvani et al used a Martinez-type stretcher in a Tm:YAG crystal based regenerative amplifier, in which the pulse duration was stretched to 100 ps [21]. Huang et al stretched the 3 μm pulse duration from 126 fs to 13 ps by using a Martinez-type stretcher in an Er: ZBLAN fiber-based nonlinear CPA system [22]. The best solution to these issues is to find some effective alternatives of the pulse stretchers that are fiberized and with high compactness

Methods

Results

Conclusion