Cladding-pumped Raman fiber laser with 0.78% quantum defect enabled by phosphorus-doped fiber

Abstract

Quantum defect (QD) is an important issue that demands prompt attention in high-power fiber laser. Large QD may aggravate the thermal load in the laser, which would impact the frequency and amplitude noise, mode stability and threaten the security of high-power laser system. Here, we propose and demonstrate a cladding-pumped Raman fiber laser (RFL) with QD <1%. Using the Raman gain of the boson peak in a phosphorusdoped fiber to enable the cladding pump, the QD is reduced to as low as 0.78% with a 23.7 W output power. To our knowledge, this is the lowest QD ever reported in claddingpumped RFL. Furthermore, the output power can be scaled to 47.7 W with a QD of 1.29%. This work not only offers a preliminary platform for the realization of high-power low-QD fiber laser, but also proves low-QD fiber laser's great potential in power scaling.

Functional Fibers and Functional Fiber-Based Components for High-Power Lasers

“…An increased understanding of how manufacturing method influences the properties of these materials benefits new fibers generated from new compositions. Moreover, it has been reported that the quantum defect induced high thermal load in HPFLs can be effectively eliminated in phosphorus-doped fiber [480][481][482][483][484][485][486][487][488] and over the hundred-watt level fiber laser with less than 1% quantum defect [486] has been demonstrated. From a more intrinsic view of light-matter interactions, the increment of both P 2 O 5 and B 2 O 3 continues to reduce heat generation and decreases the value of dn/dT [36,37], which suppresses the induction to parasitic effects such as SBS and TMI as well.…”

“…In addition to developing fiber lasers with higher output power and multi-dimensional controllability, there is an urgent demand for real-time analysis of laser beam characteristics, i.e., the mode decomposition (MD) [483][484][485][486][487][488][489][490][491]. Beam characterization represented by MD technology and beam quality measurement is an important tool for further study of fiber lasers.…”

Contribution of different factors in heat production in Yb3+-doped fiber laser: a review

“…19 The QD is one of the most important heat sources in gain fibers, which could result in serious thermal effects on FLs, such as the thermal lens effect, thermal MI, and additional noise. 20 The QD limits the conversion efficiency, but more importantly, it is the main source of thermal load in FLs. 31 Karimi: Contribution of different factors in heat production in Yb 3+ -doped fiber laser: a review Optical Engineering 110902-2 November 2022 • Vol.…”

“…Different techniques can mitigate thermal effects, such as water cooling, thermoelectric cooling, and anti-Stokes fluorescence cooling 19 . Using RFLs instead of doped FLs reduces QD up to 95% 20 …”

“…19 Using RFLs instead of doped FLs reduces QD up to 95%. 20 In previous works, different definitions of the heat source in FLs were classified, and their simulation results were compared with each other. 21 In this work, the PD loss is added to the rate equations as a power decreasing factor, and under these changes, the effect of cavity parameters, such as core and first clad sizes, laser length, and the reflectors at the end of FL in heat distribution, is investigated in the same bidirectional pump scheme.…”