The terahertz spectra of crystal compounds including gypsum, bluestone, copperas, mirabilite and alum were studied experimentally, and absorption coefficient and refractive index of the materials are discussed. The results show that terahertz radiation has a good absorbency to these crystal compounds, and this provides possible evidence for the fabrication of terahertz absorbent materials.

Energy concentration degree which can evaluate the beam quality is significant while analyzing the energy transmission of the beam. The accurate integral expression of energy concentration degree η of nonparaxial scalar beam diffracted by circle aperture is deduced by accurate definition of light intensity. Detailed numerical calculations are carried out to discuss the law of η versus diffraction aperture ρο and transmission distance z. It’s shown that η increases monotonously with the increase of z only under some conditions. η does not increase monotonously with the increase of ρο and it gets the extremum if ρο is taken as a special value. The approach to get the largest energy and energy concentration degree of a spot is given by controlling the parameters ρο and z．

By using Lie’s invariance infinitesimal criterion, the continuous equivalence transformations of a class of nonlinear KdV-Burgers equations with variable coefficients are obtained. The differential invariants of order 1 are constructed and the group classification are made starting from the equivalence algebra. At last some general class of variable coefficient nonlinear KdV-Burgers equations are mapped to constant-coefficient Burgers equation, KdV equation and KdV-Burgers equation. In particular, some exact solutions of the variable coefficients KdV-Burgers equation are obtained.

Based on the auxiliary equation method, combining with function transformation, new solitary solutions and triangular function solutions of combined KdV equation with variable coefficients term was obtained with the help of symbolic computation system Mathematica. It is of significance to seek solitary solutions and triangular function solutions of other nonlinear evolution equations with variable coefficients term.

The first pulse problem is very popular in high repetition rate Q-switched laser, which is negative in the industry application. And it also leads to unnecessary energy loss. The mechanism of the first pulse control is analyzed on the partly end pumped E/O q-switched slab laser based on laser rate equations. A model of laser pulse generating is set up, by which the first pulse can be controlled by applying modulated high voltage on Pockels cell. The results of theory and experiments are also given.

A fiber-coupled LDA-pumped, type-I critical phase matched LBO crystal intra-cavity frequency doubled blue Nd:YAG laser at 473 nm is reported. By using a folded three-mirror cavity, with injection pump power of 12.5 W, TEM00 mode blue laser at 473nm of 1.38 W is obtained by optimizing design, with the optical conversion efficiency up to 11%.

A laser-diode(LD) pumped Nd:YVO intracavity tripling all-solid-state Q-switched ultraviolet laser at 355 nm was studied. With 20 W of the incident pump laser, and repetition rates of 1 kHz, an output power of 80 mW is obtained with pulse width of 13 ns. And experimental results is analyzed and discussed.

A new type of Nd:Glass laser resonator was designed and demonstrated. With the corner cube array as the cavity back-end-mirror, the Nd:glass laser outputs 1.06 μm high energy laser pulse. The pulse energy is more than 500 J, the beam divergence angle is about 0.6 mrad, and the electro-optic efficiency is 2.3%. The output beam spot is not a series of approximate same-amplitude sub-pulses, but a high pulse in the middle with many lower pulses around it. Lastly, the experimental results are explained and discussed. The idea of beam coherent combination using the corner cube array resonator is put forward.

A coupling system for end-pumping double-clad fibers, formed by a collimating and a focusing lens, is presented. By analyzing the Gaussian beam output from multi-mode pigtail fiber propagation behavior, the parameters of the collimating and focusing lenses and their position relationship are designed for the mode-field matching condition between the pump beam exited from the pigtail of the LD and the guided mode in the inner clad of the double-clad fiber. With a section of undoped double-clad fiber, which has the same specifications as the doped double-clad fiber, the coupled power of 34.1 W is measured experimentally while the pump power output from LD of 50 W, and thus the coupling efficiency of the designed end-pumping coupling system is nearly to be 70%, which provides the foundation for double-clad fiber lasers.

The least square method is an essential method to compute lattice parameters with high precision. The Cohen’s least square method with or without a corrective function of diffraction angle is discussed. The normal equations of seven crystal systems, formulas to compute lattice parameters and estimate error are given. The modified Levenberg-Marquardt iteration algorithm, which is commonly applicable, with wide convergent range and fast convergent speed to compute the lattice parameters and corrective function parameters, is also given. As examples, the lattice parameters of several crystals belonging to the different crystal systems were computed，and the results showed that the least square method is a method to obtain accurate lattice parameters, and the parameters of the corrective function ChuG was computed with the modified Levenberg-Marquardt method, which shows that the method is effective to compute the corrective function parameters.

The dynamics of cold atoms interacting with external laser fields is investigated. For multilevel atoms interacting with external laser fields, e.g., [EQUATION]Li, two-fold degenerate dressed states are obtained under appropriate parameters configuration, which may be defined as spin-up and spin-down in analogy with the spin-1/2 charged system. Further analysis shows that different spin states will feel spin-dependent gauge fields. When the cold atoms move in spatially varying laser fields, the effective spin-dependent gauge potential will lead to spin Hall effects as well as observable spin Hall currents.

A theoretical study of the time-dependent probe response of a single electromagnetically induced transparency (EIT) window to double EIT windows is presented by numerically solving the equations of motion of the density matrix in a quasi-Λ-four-level configuration. There is a coherent transient process with high quantum beats. This effect can be explained using the dressed state formalism. The quantum beats result from quantum coherence effect between the levels driven by RF field. The results show that when the probe field is on resonance with a bare-state transition, the beat frequency is one-half of RF Rabi frequency in transient absorption response. While the probe field is on resonance with a dressed-state transition, which results from the atom system interaction with strong RF field, the beat frequency equals the RF Rabi frequency in transient absorption response.

The nucleotide base-pairing in DNA replication and proteins synthesis can be looked as an unsorted database search. Compared to the classical search, the quantum search was square root accelerated. Based on the classical coupled harmonic oscillators system, which corresponds to Grover quantum search algorithm, and quantum tunneling effect, the model of the nucleotide base selection and H-bond formation was proposed. In addition, the catalysis of the DNA polymerase was discussed from the point of view of quantum coherence maintained. Finally, the optimization of biological information processing through the point of informatics was proved.

The squeezing properties of the Schr?dinger cat states field interacting with Bose-Einstein condensate of two-level atom are studied by means of quantum theory. The results show that the optical field and the atomic laser of even coherent state and odd coherent state interacting with Bose-Einstein condensate appear no squeezing effects, whereas the optical fields and the atomic laser of Yurke-Stoler coherent state show squeezing effects. The intensity of the initial light field and values of the coupling constant have the influences on the squeezing properties of the field and atomic laser.

By considering the dynamic Stark shift, the effects of dynamic Stark shift of level and the squeezed light field factors Y on the fidelity of quantum state are discussed. It is shown that the evolutions of the fidelity obviously exhibit the oscillations of quantum collapse and revival. Taking the Stark shift into consideration, a comparative study of the two processes for the fidelity is presented. The fidelities of the atom, the field and the system are higher than those in the absence of the dynamic Stark shift when manipulating and communicating quantum information. Meanwhile, the periodicities of the fidelity evolutions of atom, field and the system are modulated by the intensity of the initial light field, and the impulse of the oscillation of fidelity for the field become smaller. The energy between field and atom is influenced by the squeezed light field factors.

Sudden death of entanglement between two entangled atoms independently coupled to fields is investigated in two detuning cavities. The results show that the entanglement between two atoms evolves periodically and sudden death of entanglement depends on not only the detuning but also the two atomic initial states. And the influence of the ratio of the two atom-field coupling constants on sudden death of entanglement is discussed.

The entropy evolution properties of the field in the system of a cascade three-level atom interacting with binomial field in a Kerr-like medium is studied. By numerical method, the results indicate when the atom initially in excited states, the field entropy increases with the increasing of Kerr coefficient, the quantum entanglement is improved too. However, the field entropy reduces when the parameter exceeds a certain value and the period of field entropy becomes longer. When the atom initially in levels’ superposition states, the field entropy reduces with the effect of Kerr effect and the entanglement between atom and optical field becomes lower. The field entropy could be improved unless the parameter exceeds a certain value. Then the law is the same as the case of the atom initially in excited states with the increasing of Kerr coefficient.

Using the Lagrangian function, the Hamiltonian of the inductance coupling mesoscopic circuits is given. The Hamiltonian operator is diagonalized by introducing a unitary operator. By virtue of the generalized Hellmann-Feynman theorem, the quantum fluctuations of charge and its conjugate quantity for the system at finite temperature are investigated. It is found that, the quantum fluctuations of charge and its conjugate quantity have something to do with not only the parameters of the citcuit cells, but also the temperature.

The upconversion emission characteristics of Er3+/Yb3+–codoped tellurite glasses pumped by 975 nm LD at low temperature is reported. Intense upconversion emission signals around 529 nm, 546 and 669 nm corresponding to the 2H11/2,4S3/2, and 4F9/2 transitions to the 4I15/2 ground state are observed. The green (546 nm) and red (669 nm) upconversion fluorescence has a maximum intensity enhancement of 2.198 and 1.556 times around 80 K. A monotonic decrease behavior is observed for temperatures greater than 80 K. In the same temperature range the signal at 529 nm vanishes towards the lower temperature side. Population of 4S3/2 and 2H11/2 distribution as a function of temperature are investigated and fitted well by the calculated lines. Temperature dependence of luminescence lifetimes of the 4S3/2 and 4F9/2 levels of Er3+ are studied within the temperature from 8 K to 300 K and the 4S3/2 and 2H11/2 multiplets splits are investigated by a multi-Gaussian-fit procedure.

The survivability of multi-domain optical networks is the key issue for assessing the optical networks performance, which has a close relationship with real deployment. It becomes the most stringent problem, which must be resolved as soon as possible. Focused all the attention on survivability schemes under the high speed, multi-service-driven multi-domain optical networks environment, and based on the traits which are multi-service and distributed control for optical network, we analyze the problems and challenges of survivability in multi-domain optical networks. The classification of survivability problems is researched in multi-domain optical networks. According to the requirement of resilience for multi-domain optical networks, associated key techniques are classified and some core techniques are discussed. Moreover, the direction for future work is indicated.

Based on one-dimensional quadratic congruence code performance of frequency-hop time-spread codes of QCC/QCC and QCC/OOC was analyzed. By calculating the number of hits of codewords in different situation, the mean value of cross-correlation is deduced, and the bit error ratio for two types of two-dimensional codes of QCC was simulated and compared. The simulation results show that compared with QCC/QCC, the performance of QCC/OOC is better and capacity is larger, but the number of frequency-hop chips is larger when the code length is determined. When the capacity of code family is determined, the performance of QCC/QCC with large value of ρ is better, but code length of it is longer.