All-optical pulse generation opens up a field for ultrawideband (UWB) applications. However, controllable pulse width and pulse type are still challenging. Here, we present a theoretical model and stimulated results of monocycle and doublet waveforms generation using programmable optical photon echo progress. We synthesized instantaneously monocycle and doublet waveforms by adjustment of pulse width, pulse amplitude, pulse position, and time interval of subpulses. We verified the possible application of the proposed method to design U.S. Federal Communications Commission-compliant UWB waveforms, and therefore, it may provide an avenue for waveform generation.
Spectral hole characteristics of Tm<sup>3+</sup>: YAG under cryogenic temperature was studied. Higher temperature broadens hole width exponentially while leads to hole depth decay, and spectral hole disappeared above 11.2 K. Measurement confirms the prediction.
A PPKTP crystal was used to efficient green emission. Spectrum characteristics of FF and SH wave was analyzed, and phase-matching wavelength shift results from thermally-induced poling period shift. A conversion efficiency of 26.1% can be achieved.
The explicit formula solutions of cascaded third-harmonic generation (THG) process were derived based on coupled-wave equations. Conversion efficiency (CE) with the simultaneous temporal walk-off effect is theoretically investigated by use of split-step Fourier transform method, and the obtained results show that the CE of cascaded THG can be adjusted by phase mismatch, i.e., ΔkSHG and ΔkTHG. The walk-off effect can be eliminated to some extent by optimizing pump intensity. Using the multiple-grating periodically poled MgO-doped lithium niobate (MgO: PPLN), pumped by 50 fs optical parametric amplifier pulses, the CE of the cascaded THG was achieved (10.8%), and a detailed analysis was presented.
We present in this paper the fabrication and characterization of thermally stable double line waveguides in Z-cut periodically poled Lithium Niobate crystals. The waveguides were fabricated by using a femto-second laser, and utilized for second-harmonic generation. Our experiments have shown that a quasi-phase matching wavelength of 1548.2 nm, a tuning bandwidth of 2 nm, and a tuning temperature range of 150.4±1.6°C can be achieved.
The numerical study of annealed proton exchanged (APE) waveguide in Z-cut periodically poled LiNbO<sub>3</sub> is presented using finite element method (FEM), compared with beam propagation method (BPM). Also given the analysis of the effects of different annealed time and annealed temperature on modes distribution.
Self similar mode locked fiber laser is studied based on a numerical model. By introducing a dimensionless factor k to
characterize the pulse, the self similar pulse formation and its temporal and spectral changes are investigated throughout
the cavity. The influences of all the elements inside the cavity on the pulse formation are also studied.
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