The 1319 and 1338nm dual-wavelength operation of neodymium-doped yttrium aluminum garnet (Nd:YAG) ceramic and single-crystal lasers was experimentally compared. It was found that, although the single-crystal lasers preferably to oscillate at 1319nm under strong pumping, the ceramic lasers tend to operate at 1338 nm, indicating the existence of a subtle difference between the ⁴F_3/2-⁴I_13/2 transitions of the Nd³⁺ ions in the Nd:YAG crystal and ceramic lasers.

Yanmin Duan;Haiyong Zhu;Changwen Xu;Hao Yang;Dewei Luo;Hui Lin;Jian Zhang;定元 汤

Applied Physics Express

2013-1

Due to the weak birefringence of single mode fibers, solitons generated in fiber lasers are indeed vector pulses and exhibit periodic parameter change including polarization evolution even when there is a polarizer inside the cavity. Period doubling eigenstates of solitons generated in a fiber laser mode-locked by the nonlinear polarization rotation, i.e., period doubling of polarization components of the soliton, are numerically explored in detail. We found that, apart from the synchronous evolution between the two polarization components, there exists asynchronous development depending on the detailed operation conditions. In addition, period doubling of one polarization component together with period-one of another polarization component can be achieved. When the period tripling window is obtained, much complexed dynamics on the two polarization components could be observed.

Xiongquan Yao;Lei Li;Andrey Komarov;Mariusz Klimczak;定元 汤;德元 沈;Lei Su;Luming Zhao

Optics Express

2020-3-30

Efficient laser operation of Nd:Lu₂O₃ ceramic fabricated by Spark Plasma Sintering (SPS) was demonstrated. Transparent Nd:Lu₂O₃ ceramic was successfully fabricated by Spark Plasma Sintering and its laser experiment was done. On the ⁴F_3/2 to ⁴I_11/2 transition, the obtained maximum output is 1.25W at the absorbed pump power of 4.15W with a slope efficiency of 38% and two spectral lines at 1076.7nm and 1080.8nm oscillated simultaneously. The slope efficiency of 38% is near two times higher than the previously demonstrated SPSed Nd:Lu₂O₃ ceramic lasers. On the ⁴F_3/2 to ⁴I_13/2 transition, the laser operated at the wavelength of 1359.7nm and the maximum output of 200mW was obtained at the absorbed pump power of 2.7W.

Changwen Xu;Chengdong Yang;Han Zhang;Yanmin Duan;Haiyong Zhu;定元 汤;Huihui Huang;Jian Zhang

Optics Express

2016-9-5

Ho:Y₂O₃ ceramics were prepared using co-precipitated powders, with ammonium sulfate as dispersant. Y³⁺ was co-precipitated together with Ho³⁺ and Zr⁴⁺ to produce precursors, which were calcined at 1100-1400 °C to produce yttria-based powders. At calcination temperatures of ≤1300 °C, agglomeration of powders was not observed. When the temperature was increased to 1400 °C, severe agglomeration was detected. Densification was closely related to the calcination temperature: a lower calcination temperature resulted in a faster densification of ceramics to the relative density of 99.7%. The ultimate densification to ∼100% was also closely related to powders' impurity level and agglomeration. Grain growth was mainly determined by sintering temperature, but not by the initial crystallite size of powders. The optimal calcination temperature was 1300 °C, at which the obtained Ho:Y₂O₃ powder was free from agglomeration. Using this powder, the resultant Ho:Y₂O₃ ceramics showed pore-free microstructure and good optical transparency.

Jun Wang;Jian Zhang;Kaijie Ning;Jie Ma;Dewei Luo;Danlei Yin;Hao Yang;定元 汤;Ling Bing Kong

Ceramics International

2016-7-1

We report on a diode end-pumped passively mode-locked Nd : GdVO₄ laser. By using a GaAs wafer simultaneously as the saturable absorber and the output coupler, stable continuous-wave mode locking was achieved. The pulse width was measured to be 18.9 picoseconds at a repetition rate of 370 MHz. The most remarkable property of the laser is that its repetition rate can be changed from 370 MHz to 3.348 GHz by simply changing the cavity length. An average output power of 3.46 W at a 3.348 GHz repetition rate was obtained with a 14 W pump power. To our knowledge, this is the first demonstration of a passively mode-locked Nd : GdVO₄ laser using a GaAs wafer as the saturable absorber.

J. Kong;定元 汤;S. P. Ng;B. Zhao;L. J. Qin;X. L. Meng

Applied Physics B: Lasers and Optics

2004-7

This paper reports an injection-locked laser (ILL) device constructed by the MEMS technology to provide a wavelength-stabilized laser source for the atomic watches. The device mainly consists of a MEMS tunable laser and a FP laser chip by a scheme of external injection. The combination of the injection locking and the MEMS technology brings about stabilized wavelength (< ± 0.002 nm) at a small size (3 mm × 2 mm × 0.6 mm); both are crucial for the atomic watches.

X. M. Zhang;A. Q. Liu;H. Cai;C. Lu;定元 汤

2005

Room temperature 2.7 μm CW lasing of diode pumped 3at.% Er:Lu2O3 ceramic laser was demonstrated. Low erbium concentration doped materials may provide more favourable conditions for cooperative lasing at 3 and 1.6 μm.

Haitao Huang;Li Wang;德元 沈;Jian Zhang;定元 汤

2014-11-16

We report on the numerical results of period timing bifurcations in a dispersion-managed (DM) fiber laser with zero group velocity dispersion (GVD).The fiber laser is passively mode-locked by using the nonlinear polarization rotation technique. Period-Tripling bifurcation route to chaos is numerically observed apart from the conventional period-doubling bifurcation route to chaos. The small signal gain is the only varying parameter, while all the other cavity parameters are fixed. Different from the conventional period-doubling bifurcation route to chaos where the route begins from order, the period-Tripling bifurcation route to chaos is led by a direct route from period one to chaos and then to a period-Tripling state. The appearance of nonlinear window of period-Tripling suggests that the ultrashort pulses generated from the DM fiber laser with zero GVD have rich nonlinear dynamics.

Qian Zhang;Lei Li;定元 汤;Luming Zhao

IEEE Photonics Journal

2016-12

We show numerically that when a soliton circulating in the laser cavity experiences dynamical bifurcations, extra sets of sidebands appear in the soliton spectrum. The new sidebands have clearly different characteristics to those of the conventional soliton sidebands, indicating that there exists a new mechanism of sideband generation in the lasers.

定元 汤;J. Wu;L. M. Zhao;列加 钱

Optics Communications

2007-7-1

Well-dispersed Nd:Y₂O₃ powders with uniform particle size of about 60 nm were synthesized from freeze-dried precursors. Highly transparent 2 at.% Nd:YAG ceramics were fabricated from the as-synthesized Nd:Y₂O₃ powders and commercial Al₂O₃ powders by vacuum sintering at 1,750 °C for 5 h. Phase evolution, microstructures, and spectroscopic properties of the Nd:YAG transparent ceramics were investigated. Freeze-drying played an important role in the synthesis of high-quality Nd:Y₂O₃ nanosized powders, which were essential for the fabrication of highly transparent Nd:YAG ceramics. Optical transmittance of a 3-mm thick sample reached 82% in the wavelength range of 200-900 nm. 5.23 W output power was obtained with 14.3 W diode laser pumping, giving a slope efficiency of 36.5%.

Hua Gong;Jian Zhang;定元 汤;Guo Qiang Xie;Hui Huang;Jan Ma

Journal of Nanoparticle Research

2011-9