2019, Zhao, Yongguang, Chen, Weidong, Wang, Li, Wang, Yicheng, Pan, Zhongben, Dai, Xiaojun, Yuan, Hualei, Cai, Huaqiang, Zhang, Yan, Bae, Ji Eun, Park, Tae Gwan, Rotermund, Fabian, Loiko, Pavel, Serres, Josep Maria, Mateos, Xavier, Shen, Deyuan, Griebner, Uwe, Petrov, Valentin

Bilayer graphene synthesized by chemical vapor deposition is successfully applied as a saturable absorber (SA) for the passive mode-locking of a Tm,Ho:CLNGG laser at 2093nm. Near transform-limited pulses as short as 70 fs, i.e., 10 optical cycles, are produced at a 89 MHz repetition rate with 69 mW average output power. To the best of our knowledge, these are the shortest pulses ever reported from graphene-SA mode-locked Tm, or Ho-lasers in the 2 µm spectral region, including bulk and fiber lasers.

2022, Zhang, Ning, Liu, Shande, Wang, Zhanxin, Liu, Jian, Xu, Xiaodong, Xu, Jun, Wang, Jun, Liu, Peng, Ma, Jie, Shen, Deyuan, Tang, Dingyuan, Lin, Hui, Zhang, Jian, Chen, Weidong, Zhao, Yongguang, Griebner, Uwe, Petrov, Valentin

We demonstrate a widely tunable and passively mode-locked Tm:Y2O3 ceramic laser in-band pumped by a 1627-nm Raman fiber laser. A tuning range of 318 nm, from 1833 to 2151 nm, is obtained in the continuous-wave regime. The SESAM mode-locked laser produces Fourier-transform-limited pulses as short as 75 fs at ∼ 2.06 µm with an average output power of 0.26 W at 86.3 MHz. For longer pulse durations of 178 fs, an average power of 0.59 W is achieved with a laser efficiency of 29%. This is, to the best of our knowledge, the first mode-locked Tm:Y2O3 laser in the femtosecond regime. The spectroscopic properties and laser performance confirm that Tm:Y2O3 transparent ceramics are a promising gain material for ultrafast lasers at 2 µm.

2020, Zhao, Yongguang, Wang, Li, Chen, Weidong, Wang, Jianlei, Song, Qingsong, Xu, Xiaodong, Liu, Ying, Shen, Deyuan, Xu, Jun, Mateos, Xavier, Loiko, Pavel, Wang, Zhengping, Xu, Xinguang, Griebner, Uwe, Petrov, Valentin

We report on a high-power Ho:YAG single-crystal fiber (SCF) laser inband pumped by a high-brightness Tm-fiber laser at 1908 nm. The Ho:YAG SCF grown by the micro-pulling-down technique exhibits a propagation loss of at. A continuous-wave output power of 35.2 W is achieved with a slope efficiency of 42.7%, which is to the best of our knowledge the highest power ever reported from an SCF-based laser in the 2 spectral range. © 2020 The Author(s). Published by Cambridge University Press in association with Chinese Laser Press.

2022, Zhang, Ning, Wang, Zhanxin, Liu, Shande, Jing, Wei, Huang, Hui, Huang, Zixuan, Tian, Kangzhen, Yang, Zhiyong, Zhao, Yongguang, Griebner, Uwe, Petrov, Valentin, Chen, Weidong

We report on a semiconductor saturable absorber mirror mode-locked Tm:(Lu,Sc)2O3 ceramic laser in-band pumped by a Raman fiber laser at 1627 nm. The nonlinear refractive index (n2) of the Tm:(Lu,Sc)2O3 ceramic has been measured to be 4.66 × 10-20 m2/W at 2000 nm. An average output power up to 1.02 W at 2060 nm is achieved for transform-limited 280-fs pulses at a repetition rate of 86.5 MHz, giving an optical efficiency with respect to the absorbed pump power of 36.4%. Pulses as short as 66 fs at 2076 nm are produced at the expense of output power (0.3 W), corresponding to a spectral bandwidth of 69 nm. The present work reveals the potential of Tm3+-doped sesquioxide transparent ceramics for power scaling of femtosecond mode-locked bulk lasers emitting in the 2-μm spectral range.

2022, Lin, Zhang-Lang, Xue, Wen-Ze, Zeng, Huang-Jun, Zhang, Ge, Zhao, Yongguang, Xu, Xiaodong, Xu, Jun, Loiko, Pavel, Mateos, Xavier, Lin, Haifeng, Petrov, Valentin, Wang, Li, Chen, Weidong

We report on sub-30 fs pulse generation from a semiconductor saturable absorber mirror mode-locked Yb:YAP laser. Pumping by a spatially single-mode Yb fiber laser at 979 nm, soliton pulses as short as 29 fs were generated at 1091 nm with an average output power of 156 mW and a pulse repetition rate of 85.1 MHz. The maximum output power of the mode-locked Yb:YAP laser amounted to 320 mW for slightly longer pulses (32 fs) at an incident pump power of 1.52 W, corresponding to a peak power of 103 kW and an optical efficiency of 20.5%. To the best of our knowledge, this result represents the shortest pulses ever achieved from any solid-state Yb laser mode-locked by a slow, i.e., physical saturable absorber.