Zhuang Zhuo

Dual-loss-modulated Q-switched and mode-locked YVO 4 /Nd:YVO 4 /KTP green laser with EO and Cr 4+ :YAG saturable absorber

By simultaneously employing the electro-optic (EO) modulator and Cr(4+):YAG saturable absorber, a diode-pumped dual-loss-modulated Q-switched and mode-locked (QML) YVO(4)/NdYVO(4)/KTP green laser is presented. In comparison with the singly passively QML green laser with Cr(4+):YAG, the dual-loss-modulated QML green laser with EO and Cr(4+):YAG can generate more stable pulse train with deeper modulation depth, shorter pulse width, greater pulse energy and higher peak power. For the dual-loss-modulated QML green laser, at a pump power of 18 W and a repetition rate of 1 kHz, the pulse width and the pulse energy of the Q-switch envelope as well as the peak power of QML green laser are 42.1 ns, 360 microJ and 382 kW, respectively, corresponding to the pulse width compression 62%, the pulse energy improvement 10 times and the QML peak power increase 40 times when compared with that of the singly passively QML green laser.

Passively mode-locked performance of a diode-pumped Nd:Lu 0.15 Y 0.85 VO 4 laser

The mode-locking performance of a diode-pumped Nd:Lu0.15Y0.85VO4 laser is first demonstrated with a semiconductor saturable absorber mirror (SESAM). Stable mode-locking with the pulse duration of 5.1 ps and the repetition rate of 106 MHz is achieved. An output power of 7 W is obtained at a pump power of 20 W, corresponding to an optical conversion efficiency of 35%. The maximum mode-locked pulse energy is estimated to be 66 nJ with the peak power of 12.9 kW.

Passively Q-switched fiber laser based on graphene saturable absorber

A passively graphene Q-switched Erbium doped fiber laser around 1.5 μm is demonstrated in this paper. The graphene saturable absorber was fabricated by sandwiching a thin graphene film produced via chemical vapor deposition between two FC fiber connectors. Stable pulse trains were obtained with the pulse repetition rate varying between 34.72 and 53.2 kHz and the average output power ranging from 0.504 mW to 0.926 mW. The achieved shortest pulse duration and highest pulse energy were 3.2 μs and 17.41 nJ, respectively.

Diode-pumped passively Q-switched Nd:YVO4 laser with a carbon nanotube saturable absorber

A diode end-pumped passively Q-switched Nd:YVO4 laser with a transmission-type single-walled carbon nanotube saturable absorber is first demonstrated in this paper. The maximum continuous wave (CW) output power of 477 mW is obtained at the incident pump power of 1490 mW with the output transmission T = 10%, resulting in slope efficiency of 41.3%. For Q-switching operation, the measured pulse duration of 332 ns, the pulse energy of 326 nJ and the peak power of 982 mW are respectively obtained.

Diode-pumped doubly Q-switched YVO4/Nd:YVO4 laser with BBO electric-optic Q-switch and Cr4+:YAG saturable absorber

In the experiment, we have demonstrated the performance of a laser-diode, end-pumped, doubly Q-switched YVO4/Nd:YVO4 laser with both a BBO electric-optic (EO) Q-switch and Cr4+:YAG saturable absorber. At a maximum incident pump power of 15 W and an EO Q-switch repetition rate of 8 kHz, the stable laser pulses with the pulse duration 5.28 ns, the single pulse energy 0.14 mJ, and the pulse peak power 26 kW are obtained. The experimental results show that the double Q-switched laser with EO and Cr4+:YAG can generate the shorter pulse and the higher peak power in comparison to singly Q-switched laser with EO.

Investigation of pulse splitting behaviour in a dissipative soliton fibre laser

Pulse splitting in a dissipative soliton fibre laser taking the nonlinear polarization evolution (NPE) rejection port as the output is investigated. Both numerical and experimental results show that with enhancement of the NPE effect, the pulse and its spectrum from the rejection port will split into two parts, which are the wings of the intra-cavity circulating pulse. It is consistent with what we expect from nonlinear polarization rotation acting on the pulse. However, to the best of our knowledge, this is the first systematic report on this phenomenon. Numerical simulation results show that when the output pulse splits into two sub-pulses, the evolution of the intra-cavity pulse is totally different from the case in which the rejected pulse has a high-quality intensity profile.

Cross-splicing method for compensating fiber birefringence in polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution.

We propose a cross-splicing method, for the first time to our knowledge, to compensate the effect of fiber birefringence in a polarization-maintaining fiber ring laser mode locked by nonlinear polarization evolution. This method has been investigated numerically and experimentally. The results indicate that stable mode-locking pulses can be obtained in the cavity with this method; otherwise, no mode-locking states are achieved. The design processes of the laser cavity are presented. Pulses with single pulse energy of 2.1 nJ are generated at pump power of 460 mW. The spectral bandwidth and pulse duration are 17.5 nm and 11.7 ps, respectively. The tunability of the laser is also studied. The central wavelength can be tuned from 1023.2 to 1045.9 nm.

A passively mode-locked Nd:YVO4 laser with a carbon nanotube saturable absorber

We report the mode locking of a diode pumped Nd:YVO4 crystal laser by using a transmission-type single-walled carbon nanotube saturable absorber. The laser operated at 1064 nm pumped by a fiber coupled laser diode with the cavity length of 1826 mm, generated a pulse width of 14 ps at a repetition rate of 82 MHz. The output power of 120 mW was obtained at the absorbed pumping power of 1400 mW.

Three Multiple-Pulse Operation States of an All-Normal-Dispersion Dissipative Soliton Fiber Laser

Multiple-pulse operation states of an all-normal-dispersion Yb-doped double-clad dissipative soliton fiber laser are investigated in this paper. The proposed laser can deliver harmonic mode-locked pulses, bound states of dissipative solitons, and dual-wavelength dual-pulses. Stable second-harmonic and third-harmonic mode-locked pulse trains are obtained with the output power of 1.39 W and 1.46 W, respectively, and the corresponding single pulse energies are 12.1 nJ and 8.5 nJ. With the adjustment of pump power and the wave plates, the fiber laser generates bound states of two or three dissipative solitons. Moreover, a dual-wavelength dual-pulse state is presented, where the output pulses from the nonlinear polarization rotation rejection port consists of the leading and trailing edges of the pulses circulating in the cavity.

Diode-pumped Q-switched Nd:Y0.5Lu0.5VO4 laser double-modulated with an acousto-optic modulator and Cr4+:YAG saturable absorber

A diode pumped Nd:Y0.5Lu0.5VO4 pulse laser modulated with an acousto-optic (AO) Q-switcher and Cr4+:YAG saturable absorber is first demonstrated in this paper. The laser is shown to generate shorter pulse width than AO Q-switched laser alone, and have a higher peak power and single pulse energy than passively Q-switched laser with only Cr4+:YAG. A laser pulse width of 6.16 ns and a peak power of about 43.83 kW are achieved at the incident pumping power of 14.09 W.