High power downconversion deep-red emission from Ho3+-doped fiber lasers

Shuaihao Ji,Bo Xiao,Zhongyu Wang,Zhiping Cai,Qichen Feng,Huiying Xu,Yingyi Song,Chenyao Shen,Jiazhen Lin,Qingyang Du

doi:10.1515/nanoph-2021-0763

Abstract

Abstract It has been a big challenge in decades for Ho3+-doped fiber laser to produce high emission power in deep-red due to its intrinsic long carrier lifetime in 5I7 energy level. Here, we advance the development of this visible fiber lasers by a novel pumping method that leverages the advantages of blue laser diode downconversion mechanisms to fully pumping, while shortening the lifetime of the lower energy level of the deep-red laser through excited state absorption. For the first time, we demonstrate a downconversion fiber laser using a single wavelength of 532 nm solid-state laser pump source to excite the Ho3+-doped ZBLAN fiber, which achieves a record high maximum output power of 1.64 W at 752.10 nm, as well as free-running of deep-red lasers with watt-level output. This technology represents a milestone in high power deep-red fiber lasers. Importantly, it is readily to be extended to other wavelengths that evidenced its huge application potentials in fiber laser industry.

Highlights

High power fiber lasers have made important advances and applications in the near to mid-infrared region, relying on the mature industrial base of rare earth doped fibers, low attenuation of light and precise parameter control to achieve high pumping efficiency assurance
We advance the development of this visible fiber lasers by a novel pumping method that leverages the advantages of blue laser diode downconversion mechanisms to fully pumping, while shortening the lifetime of the lower energy level of the deep-red laser through excited state absorption
We demonstrate a downconversion fiber laser using a single wavelength of 532 nm solid-state laser pump source to excite the Ho3+doped ZBLAN fiber, which achieves a record high maximum output power of 1.64 W at 752.10 nm, as well as free-running of deep-red lasers with watt-level output

Summary

Introduction

High power fiber lasers have made important advances and applications in the near to mid-infrared region, relying on the mature industrial base of rare earth doped fibers, low attenuation of light and precise parameter control to achieve high pumping efficiency assurance. Watt-level fiber laser output has been achieved by different rare-earth ions doping in the visible wavelength band less than 650 nm. By comparing the blue LD downconversion and red solid-state upconversion pumping mechanisms, we are convinced that this method introduces a new approach of achieving fiber laser output in the visible band in terms of improved laser output characteristics and increased energy conversion efficiency. This technology will be suitable for high-power green solid-state pumped double-cladding Ho:ZBLAN fibers that can be used to realize the scalable power improvement of deep-red lasers

Theoretical analysis and experimental principle

Experimental setup

High output performance of deep-red fiber laser

Output characteristics of deep-red fiber lasers with different designs

Conclusions