Mg doped ZnO thin films were prepared by magnetron sputtering and were irradiated by linearly polarized femtosecond laser pulse. Scanning electron microscopy (SEM) characterizations illustrated that regularly arranged nanoripples appeared on the ablation area with the period perpendicular to the polarization direction in the range of 250 nm~570 nm, but parallel to the polarization direction in the range of 2.2 µm~2.5 µm. The redshift of Raman peaks was observed at the central ablation area of the nanoripples, while, both blueshift and redshift were found at the edge area, which could be ascribed to the defects as well as the nanoripple structure.
We derive and calculate numerically laser linewidth by means of the laser rate equation in an extending diode laser
cavity provided by an end reflector. We found that narrow linewidth is closely connected with phase modulation and
frequency modulation. The numerical simulation shows the dominance of effect over another depends on inherent factors
such as the α coefficient, bandwidth of laser, length of external cavity, reflective coefficient etc.
A mode hop free tunable blue laser at 465 nm based on an external cavity system is investigated. The single longitudinal
mode second-harmonic generation (SHG) blue laser was generated using quasi-phase matching (QPM) based MgO:
PPLN pumped by infrared diode laser at 930 nm with one lasing longitudinal mode. The wide turning rang in excess of
100 GHz is achieved by using combination the etalon, silica glass plate and narrow band filter into the external cavity,
which only allow one longitudinal mode running and operating wavelength tuning. 30 mw blue light was obtained at
wavelength of 465 nm with beam quality better then M2 =1.3.
Using the amplification transfer function of type1BaAlBO3F2 (BABF) crystal, the parametric fluorescence properties of
new BABF crystal have been investigated in the different quasi-phase matched modes. The parametric fluorescence
signal lifetime study is presented based on amplification gain obtained in the quasi-phase matched modes. This analysis
of parametric fluorescence signal lifetime is shown to be equal to the results obtained from the amplification transfer
The problem of phase-mismatch-compensation for ultra-broadband OPCPA is first studied theoretically by us, and a scheme for phase-mismatch-compensation is proposed, which is based on the matching of both the group velocity and pulse front between signal and idler by the combination of the no collinear-phase-match and pulse-front-tilt that is accomplished by angular dispersion of the interacting rays. By this Scheme, the phase mismatch to first order in frequency shift can be completely compensated, and then an ultra-broadband OPCPA is realized. It is shown that the phase mismatch to both first and second order can be completely compensated simultaneously in some cases, and this leads to an extremely broadband spectral width. Therefore the important criterion for constructing an ultra-broadband OPCPA that both pulse-front and group-velocity between signal and idler are exactly matched simultaneously. Finally, specific numerical calculations and simulations are presented for BBO-OPCPA with type-I noncollinear angularly dispersed geometry.