Passively Q-Switched Integrated Tm: YAG/Ho:YAP Laser

Haizhou Huang,Wen Weng,Yan Ge,Jinhui Li,Wenxiong Lin,Hui Zheng,Huagang Liu

doi:10.1109/jphot.2021.3130419

Abstract

We firstly propose the integration of heterogeneous Tm:YAG and Ho:YAP crystals into a single bulk structure for a compact, diode-pumped passively Q-switched (PQS) Ho laser. Efficient 2129 nm laser, with maximum CW power of 6.67 W was obtained from the Tm:YAG/Ho:YAP gain medium, with slope efficiency of 38.3% and optical conversion efficiency of 27.4% by considering the incident diode power at 785 nm. Modulated by a Cr:ZnSe saturable absorber inside a hybrid cavity, characteristic self-pulsing of the integrated Ho laser can be suppressed for a stable PQS process, where average output power of 743 mW at 2053.3 nm was obtained with shortest pulse duration of 123 ns at 14.2 kHz. As the maximum thermal stress of 48.2 MPa is far below the fracture limits of each integrated section (~160 MPa), higher laser power can be expected. The results pave the way to explore the integration of other existing Tm-doped and Ho-doped hosts for an accessible 2.1 m source.

Highlights

Q-SWITCHED Holmium (Ho) lasers are attractive in a variety of applications, such as lidar, surgeries and material processing [1]-[3], which are the ideal pump sources for non-linear frequency conversion toward 3~14 μm via supercontinuum generation [4] and optical parameter oscillation [5]
Due to the lack of absorption band at 800 nm, Q-switched Ho lasers are mainly pumped by the Thulium (Tm) lasers and 1.9 μm diode lasers (LDs) [6], [7], especially in a MOPA structure with several well-developed high-power Tm lasers [8]
Basing on a conventional two-mirror cavity consisting of EM and OC, a spectral filter (SF) was inserted intra-cavity after the Tm:YAG/Ho:YAP crystal for separating the intra-cavity Tm laser from the Ho laser

Summary

Introduction

Q-SWITCHED Holmium (Ho) lasers are attractive in a variety of applications, such as lidar, surgeries and material processing [1]-[3], which are the ideal pump sources for non-linear frequency conversion toward 3~14 μm via supercontinuum generation [4] and optical parameter oscillation [5]. Due to the lack of absorption band at 800 nm, Q-switched Ho lasers are mainly pumped by the Thulium (Tm) lasers and 1.9 μm diode lasers (LDs) [6], [7], especially in a MOPA structure with several well-developed high-power Tm lasers [8]. As additional layout for the Tm laser should be prepared for cascade pumping, compactness and accessibility.

Methods

Results

Conclusion