Terahertz (THz) waves generation and detection methods based upon ultrafast laser technology are introduced. The detection methods include free-space electro-optic sampling (EO) and air-biased-coherent-detection (ABCD). EO is based upon the electro-optic effect and it can detect THz time waveform by measuring the change of the probe laser polarization. ABCD is an three-order nonlinear optics effect and there is no frequency limitation for ABCD so it can detect broad bandwidth THz pulses. THz generation from photoconductor antenna, optical Dember effect, optical rectification and laser air-plasma interaction are introduced. And the properties of THz generation are discussed. Optics rectification with tilted pump laser pulses front excitation can generate strong THz emission. The THz pulse bandwidths are limited in the former three methods while it is broader from laser air-plasma interaction.

In atmospheric environment, the laser plasmas was generated by the ablation of Ni target by using a 532 nm pulsed Nd:YAG laser beam. The spatially-resolved emission spectrum of Ni atom in the laser induced plasma was measured in the wavelength range from 350 nm to 600 nm. The spatial-evolution of the Stark broadening of the Ni 385.83 nm emission spectral line and its radial distribution were also obtained. The electron density of plasmas was calculated from the measured intensity and Stark broadening of emission spectral line, the spatial evolution property of the electron density was discussed. It is shown that Stark broadening (line broadening and line shift) of the spectral lines and electron density increased to its maximum firstly, then decreased along the direction of laser beam when the distance of the measured zone from the target surface was in the range of 0～2.5 mm. The maximum value of Stark broadening of the spectral line and electron density appear at 1.25 mm from the target surface. The value of electron density changes in the range of 0.1～3.0×1016 cm-3.

OH-initiated photooxidation reaction of isoprene was performed in the home-made smog chamber. Isoprene and important gas phase products (methacrolein and methyl vinyl ketone (m/z=70) were monitored real time by proton-transfer-reaction mass spectrometer (PTR-MS), and formation and growth of secondary organic aerosol (SOA) were measured by scanning mobility particles sizer (SMPS). Photoionization mass spectroscopy of important gas phase products from this photooxidation of isoprene was obtained using synchrotron radiation photoionization mass spectrometry (SRPIMS). It is shown that with increase of reaction time, isoprene concentration reduced gradually, and SOA began to form and grow. When isoprene was depleted nearly, the mass concentration of SOA was still kept to grow, which indicated that heterogeneous reaction of the main gas phase products occurred on the surface of particles should be responsible for the growth of SOA.

Alcohol-water complex clusters were studied by using multiphoton ionization technique and time-of-flight mass spectrometer. Laser with 355 nm wavelength was used as ionized source, protonated cluster ions (ROH)n (H2 O)H + and (ROH)n H + were observed where R=CH3 or C2 H5 . The formation of (ROH)n (H2 O)H + is mainly through proton transfer reaction intra alcohol-water clusters ions after laser multiphoton ionization. Some possible geometric structures of (CH3 OH)n (H2 O)H + with relatively small sizes were guessed using ab initio calculation method. The structures show that (CH3 OH)H + trends as the ion’s center, and then it combines with other methanol or ethanol molecule to form the final stable complex cluster ions.

On the basis of the second-order moment of the power density, beam width, far-field divergence angle and M2 factor nonparaxial cosine-squared Gaussian beams were illustrated and analyzed with numerical simulation. The conclusions are as following. 1) The waist width W0(0) increases with increasing w0/λ parameter. W0(0) decreases with increasing decentred parameter α when w0/λ is relatively large (w0/λ≥0.5). 2) As the parameter w0/λ→0, the far-field divergence angle approaches an asymptotic value of θ0max=63.435°, which is independent of the decentred parameter α. 3) In the nonparaxial regime, the M2 factor of cosine-squared Gaussian beams depends not only on the decentred parameter α, but also on the initial waist-width to wavelength ratio w0/λ, the M2 factor may be less than 1 as w0/λ becomes small enough. The M2 factor does not always vary monotonically with w0/λ for different decentred parameter α, and it increases with increasing w0/λ and reaches the maximum value, then gradually decreases, and finally tends to be a saturated value.

A wide-tunable single-longitudinal-mode fiber laser based on ring cavity structure was presented. The unidirectional propagation of light controlled by the circulator in the ring cavity can eliminate the spatial hole burning effect effectively. For realizing single-longitudinal-mode operation in fiber laser, the compound cavities designed based on Vernier effect were adopted. For suppressing the mode hopping, the saturable absorber effect of an unpumped doped fiber was considered. Meanwhile, the fiber Bragg grating filter with a widely tuning range was used to select oscillation wavelength. With these configurations, a stable single-longitudinal-mode erbium-doped fiber laser with 10 mW output power, 0.7 kHz linewidth and 20 nm tuning range was achieved.

Based on the features of LD end-pumped Yb3+:Y2 SiO5 laser crystal and considering the convective heat transfer on the side faces, the temperature distribution, pumped-face distortion and thermal focal length under different pump power were obtained by solving anisotropy heat conductive equation through finite difference method. The thermal focal lengths before and after considering the heat-transfer coefficients were calculated respectively. And the thermal focal length was further measured experimentally. The experiment results demonstrate that the tendency of thermal focal length changing with pump power agrees well with the theoretical result.

The model for uplink propagation for the relay mirror systems was established, and the effect of aperture matching on uplink propagation for relay mirror systems was simulated and analyzed by the 4-D code for laser propagation in atmosphere. The far-field peak power density of the received beam whose distorted phase was completely removed was selected as the evaluation function of the uplink propagation process. The optimal focal lengths of different transmitting apertures were picked out based on the calculation in vacuum, and the uplink propagation in the atmosphere for different transmitting apertures with their respective optimal focal length was simulated. Results show that with a certain receiver aperture, the optimal focal length decreases while the transmitter diameter increases. The critical launching power increases with the increase of transmitter diameter. When the launching power is small, the change in transmitter diameter imposes little effect on the performance, but when the launching power is high enough, performance of the relay mirror system is improved significantly with the increase of transmitter diameter.

A series of phosphors Ca3(1-x) (PO4)2: xRE3+ (RE=Eu, Dy, Ce, Tb) were prepared by a high temperature solid-state reaction method. Their luminescence properties were investigated. The results indicated that all samples can be effectively excited by ultraviolet light with fluerescence range from blue to red light, and they are the potential phosphors to obtain white LED excited by ultraviolet light. In the range of 0.005 ～ 0.03 mol, photoluminescence quenching concentration of Eu3+ , Dy3+ , and Ce3+ -doped are 0.025 mol, 0.025 mol and 0.02 mol, respectively, and Tb3+ -doped samples has high quenching concentration.

Using a five-particle entangled state as quantum channel, the separation of quantum information of four particles W state was achieved. The sender Alice sends 2, 5 particles to Bob and sends 3 particle to Charlie. The sender Alice conducts von-Neumann measurement to six particles in hand and tells Charlie and Bob measurement results. The controller Charlie makes projection measurement to single particle in hand, then tells Bob of the measurement result. According to the results, Bob makes the appropriate operating of unitary transformation to two particle, plusing two auxiliary particles, conducting the appropriate operation of quantum gates. Through all of these operations Bob can rebuild four particle W state which is to be sent. The success probability of this project is 100%, and what’s more, it needs less particles and is easier to be accomplished.

The entangled property of Yurke-like state was investigated via spin squeezing. Since the Yurke-like state is superposed by a symmetric state and two special multi-particle states, the entangled property can be studied by investigating superposition coefficient and relative phase’s influence on spin squeezing parameter. The analytical results for the optimal squeezed direction and optimal squeezing were obtained via extremum method. It’s shown that the spin squeezing parameter monotonously changes with superposition coefficients and periodically changes with relative phase. It is also shown that the more the number of the particles is, the stronger the degree of squeezing will be.

Based on the characteristics of liquid crystal rafractive index on electric and temperature, electric field and temperature controlled characteristics of defect mode were investigated in one dimensional liquid-crystal-filled photonic crystal with a defect layer by means of transfer matrix method. The results showed that, as the temperature T is in the range from 273 K to 330 K, the wavelength of defect mode shifted to short wavelength and its variation increased with increasing of the angle θ between perpendicular incident light and electric field direction, which is in the range from 0 to π/2, and the maximum controllable value of wavelength is 37.3 nm. As θ is in the range of 0 ～π/2, the wavelength of defect mode will drift, the quantity of the drift is negative at first, and then positive with rising of external temperature T which is in the range from 273 K to 330 K and the maximum controllable value of wavelength is 21.9 nm. When θ is equal to 0.7505, no matter how to change the external temperature T which is in the range from 273 K to 330 K, the defect mode wavelength remains stable. The effect of temperature on the defect mode wavelength is weaker than that of θ between perpendicular incident light and electric field direction on it.

The analytical solutions of light beams under two-dimensional harmonic oscillator modulation were obtained with self-similar technique, and the change rules with the quantum number of transmission properties of light beams were discussed by numerical simulation when their transmission distance were taken fixed. It is found that, under two-dimensional harmonic oscillator modulation, the solutions of light beams are Hermite polynomials, whose energy peaks are the highest in the middle of the wave packet which is similar to the bright solitons, and the energy distribution forms a matrix wave packets or a square matrix wave packets in geometry. The total number of wave packets is influenced by the quantum numbers of x and y direction. The amplitude of wave packets energy increases gradually along the positive and negative direction of x and y axis and is diagonal symmetrical on the matrix, x axis or y axis.

The linear and nonlinear optical absorptions in square tangent quantum well were investigated. Analytic forms of the linear and third-order nonlinear optical absorption coefficients were derived using the compact density matrix approach method. Based on this model, the numerical results were presented for a typical AlGaAs/GaAs square tangent quantum well. The calculated results show that the shape of quantum well and incident optical intensity have great influence on the optical absorption coefficients in square tangent quantum well.

A soliton solution to (2+1)-dimensional nonlinear Schrdinger equation with variable nonlinearity coefficients based on Hirota bilinear method was obtained. The results indicate that a new family of vortex solitons can be formed in the Kerr nonlinear media in the cylindrical symmetric geometry. These soliton profiles are stable, independent of propagation distance.

Preliminary investigation for pipeline safety real-time monitoring with distributed fiber optic sensing technique based on coherent Rayleigh backscattering was carried out. On the basis of a novel one-dimensional impulse-response model of coherent Rayleigh backscattering in fiber, the influence of backscattering power curve with multiple continuous input pulses under external disturbance was explained. Coherent Rayleigh backscattering light power curve was visually presented through numerical simulations with the theoretical model. In order to demonstrate the model, an experimental measurement with 4 km-long single-mode sensing fiber was performed and the position where the disturbance occurs was easily found. To improve the SNR, a normalization method of peak-seeking with software was introduced. This method can effectively reduce average number and enhance the maximum detectable frequency range of external disturbance.

The relationship between surface-enhanced Raman scattering (SERS) power collected by the fiber Raman probe and sample position was investigated theoretically under the sample damage threshold limit by using ray tracing method. The results show that, in a given damage excitation power density threshold, the SERS power collected by the probe with different focal-length lens increases when the sample deviates from the focal plane. Furthermore, compared with the situation that the sample is away from the probe and deviate from the focal plane, SERS power collected by the probe is higher at the situation that the sample is close to the probe and deviates from the focal plane. In addition, the lager the collection fiber core diameter is, the greater the power collected by the probe will be.

The structural parameters of combination tapered optical fiber surface enhanced Raman scattering (SERS) probes were designed and optimized. By building the excitation light attenuation coefficient model based on evanescent wave excitation on the nanoparticle’s surface of combination tapered optical fiber, and considering the total refraction theory of the excited light in the gradient core section and the mode-matching principle between the probe straight core section and the excitation fiber, the structure parameters design and optimization method of the combination tapered SERS probe were presented. With given fiber, nanoparticle structure, surrounding environment and input excitation power, an example of simulation design for the structural parameters of such optical fiber SERS probes were carried out by using the presented method.

Under the effectives-mass envelope-function theory, the binding energy of the system in GaN/Alx Ga1-x N symmetric double quantum wells were theoretically calculated using the variational method. The influence of applied external electric fields, barrier height, quantum well width and the position of donors on the binding energies of donor impurities were investigated. The potential quantum well energy changes significantly with applied external electric field. The binding energy and wave functions with the donor in different positions were presented with and without external electric field. Variations of donor binding energy with the centre barrier width were also calculated. With the fixed middle barrier of double quantum wells, the binding energy increases until it reaches a maximum value, and then decreases as the well width increases. The results are meaningful in the design of optoelectronic devices based on GaN/Alx Ga1-x N quantum well structures.

Considering the influence of Rashba effect, which was brought by the spin-orbit interaction, the effective mass of bound polaron with strong-coupling between electron and phonon was expressed as a function of Rashba effect, speed and vibration frequency of polaron by using improved linear combination operator, LLP unitary transformation and variation methods. The numerical calculation results for RbCl quantum dot indicate that the effective mass and vibration frequency of bound polaron increase with increasing speed and confinement strength of polaron, as well as Coulomb bound potential, because of increasing of electronic kinetic energy with increasing polaron speed, enhancing interaction between electron and phonons with strengthening Coulomb bound potential, reducing effective range of electronic motion and increasing electronic kinetic energy with increasing confinement strength of polaron. The numerical calculation results also show that effective mass of bound poalron is split because of Rashba spin-orbit interaction, the splitting difference of effective mass decreases with increasing speed of polaron.

Power control is a key technique for resource management in wireless data networks. In order to get Pareto improvement for non-cooperative power control in wireless data networks, Stackelberg game was introduced to the power control game in wireless data networks, which makes all terminals in system work in the best equal signal-to-interference (SIR), a new distributed power control algorithm based on Stackelberg game (SPG) was presented and simulated. Numerical results suggest this algorithm can improve the capability of the system whose terminals enjoy higher utility and lower transmit power relatively. The algorithm also leads to more rational and impartial, and has good convergence.

Coherent optical orthogonal frequency division multiplexing (CO-OFDM) transmission has attracted special attention in numerous studies due to its interesting and efficient transmission performance. Wavelength-division multiplexing (WDM) technology improves system capacity by increasing the number of parallel transmission wavelength in optical fiber. The combination of coherent optical orthogonal frequency division multiplexing (OFDM) and WDM technology in optical fiber communication can build high speed rate, large capacity and low cost for optical transmission networks. Applications of theoretical model and the basic principles of WDM system using coherent optical OFDM were introduced. A simulation experiment of 100 Gb/s×32-channel WDM transmission system was derived from the coherent optical OFDM and the transmission performance of the system were studied. The simulation shows that system Q of the WDM channels at 3.2 Tb/s is potentially over 16.0 dB for a transmission up to 1500 km-long standard single mode fiber without any optical dispersion and nonlinear compensation.