Virtual Journal of Laser

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 1 March 2010
R.S., Verma , M.K., Swami , S.S., Manhas , P.K., Gupta
Mueller matrix measurements were used to characterize the polarization properties of liquid crystal-based reflective type twisted nematic (TN) special light modulator (SLM) at oblique incidence of the laser beam. The experimentally obtained Mueller matrices were used to obtain the combination of polarization optics required to optimize it for phase only modulation. The results indicate that minimum intensity modulation is obtained with the use of a polarizer followed by a quarter wave plate (QWP) in polarization state generator (PSG) arm and a QWP followed by an analyzer in polarization state analyzer arm (PSA). Polarization parameters such as retardance, rotation and depolarization...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 26 February 2010
Simon, Hachey , Christopher R., Jones , J. Nathan, Kutz
An averaged evolution equation is presented and its dynamics studied for a mode-locked laser where the intensity discrimination (saturable absorption) in the cavity is provided by phase-sensitive amplification. The phase-sensitive amplifier acts as a phase-filter for selecting the specific intensity-dependent phase-rotation of the mode-locked pulse that locks the phase to the amplifier pump phase. The resulting averaged equation is a Swift–Hohenberg type model which is a fourth-order diffusion equation with cubic-quintic nonlinearities. Additionally, the governing evolution has a new linear growth term which couples to the nonlocal cavity energy. This parameter is a standard bifurcation parameter in Swift–Hohenberg models and...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 25 February 2010
Vinod, Vukkalam , John, Houlihan
The impact of injection current profiling on the spatial mode structure of quantum dot semiconductor lasers is investigated. Numerical simulations based on a spatial extension of a simple rate equation model for quantum dot devices reveal the role of non-resonant carries in the appearance of strong dips in the optical field of the device. Symmetry breaking may also occur whereby the position of the dip shifts from the centre of the injection region.

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 24 February 2010
Long-jiang, Chen , Yi-yong, Liang , Kai-wei, Wang , Jian-bo, Luo , Chun-hui, Zhang , ...
A system of convex-surface laser lithography with diode laser is established in this paper. Based on this system, a mathematical model of optical field distribution and lithography on the photoresist layer of convex-surface substrate with diode laser is presented. According to the lithography system and model, some numerical simulations are carried out. The simulation result shows that lithographic lines on convex-surface lithography are not symmetric about the optical axis of incident laser beam. Axis of lines at different vector radius on convex-surface substrate will offset from the wavefront normal of incident laser beam. The offset distance depends on the slopes...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 February 2010
V.A., Reshetov , I.V., Yevseyev
The probability of emission of a single-photon via Raman scattering of laser pulse on the three-level Λ – type atom in microcavity is studied. The duration of the pulse is considered to be short enough, so that the hyperfine structure of the upper level remains totally unresolved, while that of the lower level is totally resolved. The coherent laser pulse is assumed to be in resonance with the transition between one hyperfine-structure component of the lower atomic level and all hyperfine-structure components of the upper level, while the quantized cavity field is assumed to be in resonance with the transition...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 February 2010
Jae Sung, Shin , Sangwoo, Park , Hong Jin, Kong
Stimulated Brillouin scattering phase conjugate mirrors (SBS-PCMs) are extensively used to compensate the phase distortion of active media in a high-energy laser system with double-pass amplification. However, the depolarization loss from the thermally induced birefringence of the active medium by a photoelastic effect cannot be avoided despite the uses of phase conjugate mirrors. In this work, the depolarization loss in a double-pass Nd:YAG rod amplifier with a SBS-PCM has been studied with Jones matrix calculations. In addition, the depolarization ratios and the leak beam patterns are obtained experimentally and theoretically for four possible optical schemes. Both experiment and theoretical results...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 February 2010
Qi, Zhu , Bailiang, Pan , Li, Chen , Yajuan, Wang , Xunyi, Zhang
Assuming the pump light to be a Gaussian beam and considering the medium absorption, we establish the heat conduction model to describe the temperature distribution in diode-pumped alkali vapor lasers (DPALs) with two different pumping ways. Combining with the experimental parameters in cesium laser, the spatial temperature distribution picture, the longitudinal and the radial temperature distributions of two cesium lasers are obtained by numerical solving the model. Influences of the pump power, the beam waist and the absorption coefficient on the axial and the radial temperature distribution are calculated and compared for the two Cs lasers. The result suggests that...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 February 2010
Yude, Li , Yunguang, Zhang , Yizhong, Kuang , Weiming, Liu , Xiouyun, Zhang , ...
First, the kinetic investigation of UF6+HCl reaction and the isotopic selectivity under CO laser irradiation is performed. On this investigation, the kinetics of UF6+HCl reaction by using an intracativity CO laser and CO2 laser irradiation system, and the isotopic selectivity for this process are studied theoretically. It is found that under the resonant CO laser and CO2 laser irradiations, the laser-catalyzed reaction rate can increase, and a good selectivity can be achieved. The uranium isotope separation factors β calculated are about 2.44∼4.05 at laser intensity 50∼100Wcm−2 and temperature 235K.

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 20 February 2010
Xing-Xia, Tian , Dong-Kang, Li , Jin-Hui, Wu
We investigate the absorption spectra of a probe laser in warm rubidium atoms driven into the four-level N configuration. Our numerical calculations show that there are six (two) coherent hole-burnings and one (two) transparency window(s) in the probe absorption spectra, when the perturbing laser co-propagates (counter-propagates) with the probe laser and both coupling and saturating lasers are exactly resonant with their driving transitions. Gradually weakening the perturbing laser, we can dramatically change the probe absorption spectra to observe more coherent hole-burnings and transparency windows as well as the conversion from transparency windows into coherent hole-burnings. Relevant phenomena can be well...

Publication year: 2010
Source: Optics Communications, In Press, Uncorrected Proof, Available online 19 February 2010
Bai-Tao, Zhang , Hai-Tao, Huang , Jian-Fei, Yang , Jing-Liang, He , Chun-Hua, Zuo , ...
A high power, quasi-continuous wave ultraviolet laser at 355nm was obtained by intracavity frequency tripling of a diode side-pumped acousto-optic (AO) Q-switched Nd:YAG laser. Type II critical phase-matched KTP and LBO crystals were used for the second harmonic generation and the third harmonic generation, respectively. Under the pump power of 180W, 7.8W average output power at 355nm was obtained at 8kHz with the pulse width of 50ns, corresponding to the pump-to-ultraviolet conversion efficiency of 4.3%. The peak power and single pulse energies were estimated to be 18.8kW and 938μJ. Its far-field divergence was measured to be about 2.1mrad. The instability...