A novel high-power all-fiberized flexible spectral filter for high power linearly-polarized Raman fiber laser

Jiaxin Song,Hanshuo Wu,Pu Zhou,Jiangming Xu,Haiyang Xu,Hanwei Zhang,Jun Ye

doi:10.1038/s41598-018-28686-2

Jiaxin Song, Hanshuo Wu + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-28686-2

Copy DOI

Journal: Scientific Reports	Publication Date: Jul 19, 2018
Citations: 7	License type: open-access

Affiliation: National University of Defense Technology

Abstract

Power scaling of linearly polarized Raman fiber laser (LPRFL), which has wide application potentials, is mainly limited by the generation of high-order Stokes light. In this paper, we propose a novel flexible spectral filter with all-fiberized configuration and high-power handling. Combining with the polarization-dependence of Raman gain, the filter could be used to efficiently suppress high-order Stokes light in LPRFL and thus help further power scaling. The filter is fabricated by two 45° cross-splice of three pieces of polarization maintaining (PM) passive fibers. The bandwidth and central wavelength of transmission spectrum of the spectral filter could be flexibly tuned through changing the length and temperature of the cross-spliced fiber. The insertion loss of the filter fabricated in the lab is measured to be as low as 0.07 dB. The filter is employed in a LPRFL, and the maximum output power of the LPRFL is increased by 48.7%.

Highlights

High power Raman fiber lasers have attracted much attentions in recent years, and have wide applications in optical communication, supercontinuum generation, special wavelength source and medicine[1,2,3]
In addition to the complex manufacturing process and high cost of polarization maintaining (PM) fibers and devices, relatively high Raman gain of linearly polarized Raman fiber laser (LPRFL) leads to low threshold of high-order Stokes light[14], which becomes a main limitation for further power scaling
We achieve efficient suppression of the high order Stokes light in high power LPRFL based on a novel all-fiber spectral filter

Summary

Introduction

High power Raman fiber lasers have attracted much attentions in recent years, and have wide applications in optical communication, supercontinuum generation, special wavelength source and medicine[1,2,3]. In addition to the complex manufacturing process and high cost of polarization maintaining (PM) fibers and devices, relatively high Raman gain of LPRFL leads to low threshold of high-order Stokes light[14], which becomes a main limitation for further power scaling. This method requires special manufacturing techniques and splicing method Another one is employing lumped spectral filters such as long period grating and tilted fiber gratings in order to couple the high order Stokes light from core mode to cladding mode[22,23,24,25]. The filter is realized by two 45° cross-splicing of three pieces of polarization maintaining (PM) passive fibers Through this filter, the polarization direction of high order Stokes light could be manipulated to be orthogonal to that of its pump light, Raman gain would be decreased[14]. The spectral filter is employed to suppress the second order Stokes light (1177.0 nm), and as a result the maximum output power of the first order Stokes light (1119.6 nm) is increased by 48.7% compared with the absence of the spectral filter

Methods

Results

Conclusion