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Liu X.,CAS Xian Institute of Optics and Precision Mechanic
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

The mechanism and intrinsic conditions of high-energy wave-breaking-free pulse generation in fiber lasers mode-locked by a nonlinear polarization rotation technique are investigated numerically and experimentally. Both numerical and experimental results show that the pulses along the two orthogonal polarization axes of the fiber have a large difference in pulse energy. The numerical simulations show that the ratio of the energy of two components is limited and ranges from about 8 to about 65. The slope of the instantaneous frequency at the central position of the pulse decreases rapidly with the increase of the pulse duration and energy, whereas the slope at the pulse edge changes slightly. The accumulation of instantaneous frequency throughout the pulse width approaches a constant in a higher pulse energy regime. Understanding the mechanism and intrinsic conditions of the wave-breaking-free pulse generation could be useful in generating high-energy pulses delivered from fiber lasers. © 2010 The American Physical Society. Source


Liu X.,CAS Xian Institute of Optics and Precision Mechanic
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We report on pulse evolution without wave breaking in a strongly dissipative-dispersive laser system where pulses encounter significant amounts of positive and negative dispersions. In contrast to conventional soliton, dispersion-managed soliton, and self-similar pulse evolutions, a different type of pulse shaping in mode-locked lasers is theoretically investigated and experimentally observed. The pulses of this laser have very low frequency chirp and exhibit as the quasirectangle temporal and Gaussian spectral profiles, and the spectral width is almost independent of the pumping strength. The temporal and spectral widths fluctuate as low as ~3% of the relative fluctuation throughout the laser cavity. Both numerical and experimental results show that the pulses exist with energies much greater than can be tolerated in self-similar pulse shaping. © 2010 The American Physical Society. Source


Liu X.,CAS Xian Institute of Optics and Precision Mechanic
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

The robust dissipative soliton molecules (DSM's) exhibiting as the quasirectangular spectral profile are investigated numerically and observed experimentally in mode-locked fiber lasers with the large normal path-averaged dispersion and the large net cavity dispersion. These DSM's have an independently evolving phase with a pulse duration T0 of about 20 ps and a peak-to-peak separation of about 8T0. Under laboratory conditions, the proposed laser delivers vibrating DSM's with an oscillating amplitude of less than a percent of peak separation. Numerical simulations show that DSM's are characterized by a spectral modulation pattern with about a 3-dB modulation depth measured as an averaged value. The experimental observations are in excellent agreement with the numerical predictions. © 2010 The American Physical Society. Source


Liu X.,CAS Xian Institute of Optics and Precision Mechanic
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The soliton formation and evolution are numerically and experimentally investigated in passively-mode-locked lasers where pulses encounter ultralong anomalous-dispersion fibers. The pulse formation and evolution in lasers are determined by two balances, namely, nonlinearity and anomalous-dispersion balance and intracavity filtering and self-amplitude modulation balance. It is numerically found that a higher-energy soliton can be split into identical lower-energy multisolitons with exactly the same physical properties. Simulation results show that the separation of neighboring solitons is variational in the temporal domain. The temporal and spectral characteristics of solitons have large variations throughout the laser cavity, qualitatively distinct from the steady state of conventional solitons. The experimental observations confirm the theoretical predictions. © 2011 American Physical Society. Source


Han X.,CAS Xian Institute of Optics and Precision Mechanic
Applied Optics | Year: 2014

I have proposed a dual-channel dispersionless slow-light waveguide system based on plasmon-induced transparency. By appropriately tuning the stub depth, two transparency windows in the transmission spectrumcan be achieved due to the destructive interference between the electromagnetic fields from the three stubs. Two flat bands can be achieved in the transparency windows, which have nearly constant group indices over the bandwidth of 2 THz. The analytical results show that the group velocity dispersion parameters of the two channels equal zero, which indicates that the incident pulse can be slowed down without distortion. The proposed plasmonic waveguide system can realize slow-light effect without pulse distortion, and thus can find important applications on slow-light systems, optical buffers, and all-optical signal processors in highly integrated optical circuits. © 2014 Optical Society of America. Source

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