Search Results
Sub-100 fs mode-locked Tm:CLTGG laser
2021, Wang, Li, Chen, Weidong, Pan, Zhongben, Loiko, Pavel, Bae, Ji Eun, Rotermund, Fabian, Mateos, Xavier, Griebner, Uwe, Petrov, Valentin
We report on the first sub-100 fs mode-locked laser operation of a Tm3+-doped disordered calcium lithium tantalum gallium garnet (Tm:CLTGG) crystal. Soliton mode-locking was initiated and stabilized by a transmission-type single-walled carbon nanotube saturable absorber. Pulses as short as 69 fs were achieved at a central wavelength of 2010.4 nm with an average power of 28 mW at a pulse repetition rate of ∼87.7 MHz. In the sub-100 fs regime, the maximum average output power amounted to 103 mW.
SESAM mode-locked Tm:Y2O3 ceramic laser
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.
Watt-level femtosecond Tm-doped “mixed” sesquioxide ceramic laser in-band pumped by a Raman fiber laser at 1627 nm
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.
35 W continuous-wave Ho:YAG single-crystal fiber laser
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.
Tm3+-doped calcium lithium tantalum gallium garnet (Tm:CLTGG): novel laser crystal
2021, Alles, Adrian, Pan, Zhongben, Loiko, Pavel, Serres, Josep Maria, Slimi, Sami, Yingming, Shawuti, Tang, Kaiyang, Wang, Yicheng, Zhao, Yongguang, Dunina, Elena, Kornienko, Alexey, Camy, Patrice, Chen, Weidong, Wang, Li, Griebner, Uwe, Petrov, Valentin, Solé, Rosa Maria, Aguiló, Magdalena, Díaz, Francesc, Mateos, Xavier
We report on the development of a novel laser crystal with broadband emission properties at ∼2 µm – a Tm3+,Li+-codoped calcium tantalum gallium garnet (Tm:CLTGG). The crystal is grown by the Czochralski method. Its structure (cubic, sp. gr. 𝐼𝑎3¯𝑑, a = 12.5158(0) Å) is refined by the Rietveld method. Tm:CLTGG exhibits a relatively high thermal conductivity of 4.33 Wm-1K-1. Raman spectroscopy confirms a weak concentration of vacancies due to the charge compensation provided by Li+ codoping. The transition probabilities of Tm3+ ions are determined using the modified Judd-Ofelt theory yielding the intensity parameters Ω2 = 5.185, Ω4 = 0.650, Ω6 = 1.068 [10−20 cm2] and α = 0.171 [10−4 cm]. The crystal-field splitting of the Tm3+ multiplets is revealed at 10 K. The first diode-pumped Tm:CLTGG laser generates 1.08 W at ∼2 µm with a slope efficiency of 23.8%. The Tm3+ ions in CLTGG exhibit significant inhomogeneous spectral broadening due to the structure disorder (a random distribution of Ta5+ and Ga3+ cations over octahedral and tetrahedral lattice sites) leading to smooth and broad gain profiles (bandwidth: 130 nm) extending well above 2 µm and rendering Tm:CLTGG suitable for femtosecond pulse generation.
Spectroscopy of solid-solution transparent sesquioxide laser ceramic Tm:LuYO3
2022, Eremeev, Kirill, Loiko, Pavel, Braud, Alain, Camy, Patrice, Zhang, Jian, Xu, Xiaodong, Zhao, Yongguang, Liu, Peng, Balabanov, Stanislav, Dunina, Elena, Kornienko, Alexey, Fomicheva, Liudmila, Mateos, Xavier, Griebner, Uwe, Petrov, Valentin, Wang, Li, Chen, Weidong
We report on a detailed spectroscopic study of a Tm3+-doped transparent sesquioxide ceramic based on a solid-solution (lutetia – yttria, LuYO3) composition. The ceramic was fabricated using commercial oxide powders by hot isostatic pressing at 1600°C for 3 h at 190 MPa argon pressure. The most intense Raman peak in Tm:LuYO3 at 385.4 cm−1 takes an intermediate position between those for the parent compounds and is notably broadened (linewidth: 12.8 cm−1). The transition intensities of Tm3+ ions were calculated using the Judd-Ofelt theory; the intensity parameters are W2 = 2.537, W4 = 1.156 and W6 = 0.939 [1020 cm2]. For the 3F4 → 3H6 transition, the stimulated-emission cross-section amounts to 0.27 × 10−20 cm2 at 2059nm and the reabsorption-free luminescence lifetime is 3.47 ms (the 3F4 radiative lifetime is 3.85 ± 0.1 ms). The Tm3+ ions in the ceramic exhibit long-wave multiphonon-assisted emission extending up to at least 2.35 µm; a phonon sideband at 2.23 µm is observed and explained by coupling between electronic transitions and the dominant Raman mode of the sesquioxides. Low temperature (12 K) spectroscopy reveals a significant inhomogeneous spectral broadening confirming formation of a substitutional solid-solution. The mixed ceramic is promising for ultrashort pulse generation at >2 µm.
Semiconductor saturable absorber mirror mode-locked Yb:YAP laser
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.
Diode-pumped sub-50-fs Kerr-lens mode-locked Yb:GdYCOB laser
2021, Zeng, Huangjun, Lin, Haifeng, Lin, Zhanglang, Zhang, Lizhen, Lin, Zhoubin, Zhang, Ge, Petrov, Valentin, Loiko, Pavel, Mateos, Xavier, Wang, Li, Chen, Weidong
We present a sub-50-fs diode-pumped Kerr-lens mode-locked laser employing a novel “mixed” monoclinic Yb:Ca4(Gd,Y)O(BO3)3 (Yb:GdYCOB) crystal as a gain medium. Nearly Fourier-limited pulses as short as 43 fs at 1036.7 nm are generated with an average power of 84 mW corresponding to a pulse repetition rate of ∼70.8 MHz. A higher average power of 300 mW was achieved at the expense of the pulse duration (113 fs) corresponding to an optical-to-optical efficiency of 35.8% representing a record-high value for any Yb-doped borate crystal. Non-phase-matched self-frequency doubling is observed in the mode-locked regime with pronounced strong spectral fringes which originate from two delayed green replicas of the fundamental femtosecond pulses in the time domain.