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.

2023, Wang, Jun, Pameté, Emmanuel, Yan, Shengli, Zhao, Wenhua, Zhang, Jianhui, He, Xiaotong, Supiyeva, Zhazira, Abbas, Qamar, Pan, Xuexue

Sodium ion insertion plays a critical role in developing robust sodium-ion technologies (batteries and hybrid supercapacitors). Diffusion coefficient values of sodium (DNa+) in tin phosphide between 0.1 V and 2.0 V vs. Na/Na+ are systematically determined by galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS), and potentiostatic intermittent titration technique (PITT). These values range between 4.55 × 10−12 cm2 s−1 and 1.94 × 10−8 cm2 s−1 and depend on the insertion/de-insertion current and the thickness of the electrode materials. Additionally, DNa+ values differ between the first and second cation insertion because of the solid electrolyte interface (SEI) formation. DNa+ vs. insertion potential alters non-linearly in a “W” form due to the strong interactions of Na+ with tin phosphide particles. The results reveal that GITT is a more appropriate electrochemical technique than PITT and EIS for evaluating DNa+ in tin phosphide.