A passively mode-locked soliton fiber ring laser with dispersion managed cavity is reported. The laser emits intense bunched noise-like pulses including the transform limited pulses. The optical spectrum of the laser emission has a bandwidth as broad as 32.10 nm. It was found that purely depending on the linear cavity phase delay the laser could be switched between the soliton operation and the noise-like pulse emission. Numerical simulations showed that the laser emission was caused by the combined effect of soliton collapse and positive cavity feedback in the laser.
定元 汤;L. M. Zhao;B. Zhao
We report on the experimental observation of a type of parametric spectral sideband generation in a continuous wave (CW) fiber laser operating in the normal dispersion regime. The appearance of the sidebands is a threshold effect and their spectral shifts from the CW wavelength vary with the cavity length and CW power. We show that the sideband formation is induced by the periodic power variation of the light in the laser cavity.
X. Hu;J. Guo;J. Ma;S. W. Yoo;定元 汤
Laser Physics Letters
We report on the experimental observation of bound states of solitons in an erbium-doped fiber laser passively mode-locked by the carbon nanotube saturable absorber. Bound states of solitons with various pulse separations are obtained. While the tightly bound solitons always exhibit the same set of fixed discrete pulse separations with π or π/2 phase difference, the feature becomes less obvious for the loosely bound solitons. The result that various states of the bound solitons were obtained in the same fiber laser makes a systematic experimental study on them and a comparison of their properties possible. Our results once again show that the bound soliton emission is an intrinsic feature of the mode-locked soliton fiber lasers.
X. Wu;定元 汤;X. N. Luan;擎 张
Yb3+ doped YAG ceramics have been successfully fabricated using a vacuum reactive sintering method. High purity Y2O3, Al2O3 and Yb2O3 powders were used as the starting materials. Samples of 5.0 at.% Yb3+ doping concentration have been obtained. The in-line transmittance of the sample reaches 84% at 1100 nm wavelength. The absorption and emission bandwidth were measured to be 19.5 nm and 11.07 nm respectively. The results show that Yb:YAG ceramics will be a promising laser material for high power and ultrafast laser applications.
Dewei Luo;Jian Zhang;Changwen Xu;Hao Yang;Xianpeng Qin;Jan Ma;定元 汤
We propose three classical coupling methods (Otto, Kretschmann, and grating configurations) to excite graphene magneto-plasmons (MPs). After MP excitation, extraordinary Kerr rotations are obtained. As a demonstration, we discuss the Otto configuration in detail, but the other two methods have similar mechanisms and are only given limited descriptions. The dispersion relations of the MPs are discussed and found to well match previous predictions. It is found that the MP excitation and critical coupling are directly responsible for the large Kerr rotations. Combining the graphene MPs and critical coupling, much larger Kerr rotations (easily above 20°) away from the cyclotron resonance are achieved, as compared to previously described Faraday rotations (below 10°) using graphene MPs. By optimizing the graphene properties and structure parameters, the Kerr rotations are further enhanced. Moreover, using the grating coupling method, we easily find the largest Kerr rotation over 50° at 3 THz. The results are calculated using the anisotropic scattering-matrix method, and the finite element method is used as a comparison. The calculation methods are discussed in detail as a basis for future studies. These results are helpful not only to better understand graphene MPs but also for their potential terahertz applications.
Jun Guo;Xiaoyu Dai;Yuanjiang Xiang;定元 汤
Journal of Applied Physics
We show experimentally that by use of an appropriately coated GaAs wafer as output coupler, either self-started passive mode locking or pulse width compression of Q-switched pulses of diode-pumped solid-state (DPSS) lasers can be achieved. Mode-locked pulses with duration in the picosecond time scale have been routinely generated in various Nd-doped DPSS lasers. Pulse width compression of the Q-switched pulses by a factor of more than three has been obtained. We have experimentally investigated the physical origin of the observed phenomena. It was suggested that they could be caused by the intensity-dependent cavity losses caused by the free-carrier-induced nonlinear refractive index grating in the wafer.
定元 汤;J. Kong;S. P. Ng
Journal of Crystal Growth
A passively mode-locked dual-wavelength Nd: GdVO4 laser with orthogonal polarizations is experimentally demonstrated. By changing the absorbed pump power, the laser can mode lock either at 1063 nm (with π polarization) or 1065 nm (with σ polarization), or simultaneously at both wavelengths with orthogonal polarizations. When mode locked at 1063 nm and 1065 nm, the laser produced pulses of 10 ps and 5.9 ps, respectively, with repetition rates of 143.7 MHz and 143.9 MHz. When simultaneously mode locked at both wavelengths, the pulsewidth was about 7 ps. The laser was demonstrated by exploiting the thermal lens and birefringence of the Nd: GdVO4 crystal. The laser uses one cavity and does not require the insertion of additional optical components.
W. D. Tan;定元 汤;C. W. Xu;J. Zhang;H. H. Yu;怀金 张
Applied Physics B: Lasers and Optics
This paper presents a short pulse-width gain-switched Ho:YAG ceramic laser at 2089 nm resonantly pumped by a homemade Q-switched Tm:fiber laser at ∼1908 nm.We generated stable pulses of 44-103 ns duration and 0.13- 2 kW peak power at 20 kHz of pulse repetition frequency when the incident pump pulse energy increased from ∼0.1 to 0.3 mJ. We also obtained an average output power of 1.76 W under an incident pump power of 6 W, corresponding to a slope efficiency of 41.8%. Finally, this paper discusses the prospects to further improve the results with even a shorter pulse-width and higher peak power.
Jianing Zhang;Qiyao Liu;德元 沈;Jian Zhang;定元 汤;Hao Chen
An in-band pumped 1.645-μm Er:YAG ceramic laser passively Q-switched by a topological insulator: Bi2Te3 saturable absorber is reported. The average output power could reach up to 210 mW, corresponding to a pulsewidth, a pulse repetition rate, and a per-pulse energy of 6.3 μ, 40.7 kHz, and 5.3 μJ, respectively. This result indicates that the topological insulator: Bi2Te3 could be a promising saturable absorber such as graphene, with potential applications for solid-state lasers.
Pinghua Tang;Xiaoqi Zhang;Chujun Zhao;Yong Wang;Han Zhang;德元 沈;双春 文;定元 汤;滇元 范
IEEE Photonics Journal
A diode-pumped passively mode-locked Nd: CTGG disordered crystal laser has been experimentally demonstrated for the first time to our knowledge. Mode locked with a semiconductor saturable absorber mirror, the laser generated 5.2 ps pulses at a repetition rate of 88 MHz. After intracavity dispersion compensation, the mode-locked pulses were shortened to 4.3 ps. Multiple emission wavelengths of the Nd:CTGG laser could be synchronously mode locked under dispersion compensation.
G. Q. Xie;定元 汤;W. D. Tan;H. Luo;S. Y. Guo;H. H. Yu;怀金 张
Applied Physics B: Lasers and Optics