Supercontinuum spectra generation in the single-mode optical fibre with concave dispersion profile

In this paper, a new method is proposed to generate broad supercontinuum （SC） spectra in the single-mode optical fibre with concave dispersion profile, We numerically simulate pulse evolutions and discuss physics mechanism in detail for SC spectrum generation in the optical fibre with concave dispersion profile. Furthermore, general criteria are presented for specifying the shape of SC spectrum by introducing normalized parameters, which are related to the fibres and the initial pump pulses. The results show that the flat and broad SC spectra are indeed generated in our proposed optical fibre.

Achieving UHF RoF communication based on restraining zero band with EO-FM modulation

We present a simple system of RoF communication based on electronic-optical frequency modulation（EO-FM） in the article. Optical system soflware-Optisystem5.0 was adopted. The results of software simulation showe that the simplex - directional 5 Gbit/s data and UHF microwave of 24 GHz were successfully transmitted over 15 km single mode fiber with 0dBm transmitted power, dispersion is 17 ps/nm/km, attenuation is 0.25 dB/km.

Ported from Self-Similar Analytic Solutions of Ginzburg-Landau Equation with Varying Coefficients

Employing the technique of symmetry reduction of analytic method, we solve the Ginzburg-Landau equation with varying nonlinear, dispersion, gain coefficients, and gain dispersion which originates from the limiting effect of transition bandwidth in the realistic doped fibres. The parabolic asymptotic self-similar analytical solutions in gain medium of the normal GVD is found for the first time to our best knowledge. The evolution of pulse amplitude, strict linear phase chirp and effective temporal width are given with self-similarity results in longitudinal nonlinearity distribution and longitudinal gain fibre. These analytical solutions are in good agreement with the numerical simulations. Furthermore, we theoretically prove that pulse evolution has the characteristics of parabolic asymptotic self-similarity in doped ions dipole gain fibres.

Phase Evolution of Coherent Light in a Simple Polariton Model

We study the phase evolution behaviour of coherent light interacting with phonons initially in thermal equilibrium at temperature T in terms of phase distribution probability. It is shown that the phase not only shifts but also diffuses. The phase distribution broadens and narrows periodically with time. There is a threshold in the variation of the width of phase distribution as a function of coupling coefficient in the detuning case for fixed temperature. The phase diffusion changes rapidly with temperature for coupling coefficient above the threshold while it changes little with temperature for coupling coefficient below the threshold.

Vacuum Rabi Oscillation of an Atom without Rotating-Wave Approximation

We have investigated vacuum Rabi oscillation of an atom coupled with single-mode cavity field exactly, and compared the results with that of the Jaynes-Cummings （J-C） model. The results show that for resonant ease, there is no Rabi oscillation for an atom. For small detuning and weak coupling case, the probability for the atom in excited state oscillates against time with different frequencies and amplitudes from that of the J-C model. It exhibits that the counter-rotating wave interaction could significantly effect the dynamic behaviour of the atom, even under the condition in which the RWA is considered to be justified.

Reply to the ＂Comment on ＇Ported from Self-Similar Analytic Solutions of Ginzburg-Landau Equation with Varying Coefficients＇＂

In view of the ＂Comment on ＇Ported from Self- Similar Analytic Solutions of Ginzburg-Landau Equation with Varying Coefficients＇＂, and referring to Refs., we reply as follows：

Experimental Study on Dual Wavelength and Dual Pulse Q-Switched Frequency Doubling on a Tunable Cr： LiSAF Laser

A flashlamp-pumped Cr：LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32m J/pulse producing the total output energy of 64mJ and the pulse width is about 27ns at 850nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength （448.1 nm and 449.15nm） and dual pulse laser. The output for one wavelength is about 10.3mJ and the line width is less than 0.02nm.

Experimental Study on Practical Quantum Key Distribution Scheme with Time-Multiplexed Technique

We present a scheme that is capable of detecting photon numbers during the quantum key distribution （QKD） based on an improved differential phase shift （DPS） system without Trojan horse attack. A time-multiplexed detector （TMD） is set in for the photon-number resolution. Two fibre loops are used for detecting photon numbers as well as distributing keys. The long-term stabilization is guaranteed by two Faraday mirrors （FM） at Bob＇s site to automatically compensate for polarization defect. Our experimental study （90km QKD is completed） indicates that such a system is stable and secure which nearly reaches the performance of a single photon scheme.

Determination of breakdown voltage of In_(0.53)Ga_(0.47)As/InP single photon avalanche diodes

We examine the saturation of relative current gain of Ino.53Gao.47As/InP single photon avalanche diodes （SPADs） operated in Geiger mode. The punch-through voltage and breakdown voltage of the SPADs can be measured using a simple and accurate method. The analysis method is temperature-independent and can be applied to most SPADs.