Simultaneous enhancement of TMI and SRS suppression enabled by tuning the refractive index profile of a low-NA YDF for high power single-mode fiber laser
Year: 2025
Type: article
Abstract: To mitigate the limitations of stimulated Raman scattering (SRS) associated with low dopant concentrations in low numerical-aperture (NA) fibers, this study proposes a central refractive index (RI) dip design for low-NA fibers to further increase the effective mode area (MFA). Through simulations of mode-field characteristics, bending-induced distortion, and bending loss, optimal dip parameters were determined. The simulations demonstrate improved transverse mode instability (TMI) and SRS thresholds in a forward tandem-pumped amplifier using this central dip fiber (CDF). Guided by these findings, a low-NA fiber with an ultra-low central dip was fabricated. Experimentally, under forward tandem pumping and optimized coiling, the amplifier achieved a 5.6 kW output with M 2 < 1.4, demonstrating significant enhancement in both SRS and TMI thresholds by using the CDF.
Source: Optics Express
DOI: 10.1364/oe.577964
Authors: Mengfan Cui, Chongwei Wang, Haobo Li, Yang Liu, Zhiyong Pan, Hu Xiao, Zilun Chen, Zhiping Yan, Baolai Yang, Pengfei Ma, Zefeng Wang, Jinbao Chen
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,270
OpenAlex ID: W4415655054