Surface Raman scattering can be enhanced by metal tip. There are few quantitative reports about the influence of tip angle on surface enhanced Raman scattering (SERS). In order to investigate the relationship between the tip angle and SERS, four kinds of samples with different tip angles, including 30°, 60°, 90°, 120° are fabricated by maskless projective lithography using digital micro-mirror device (DMD). The corresponding SERS spectra of the samples are measured, and influence of metal tip angle on SERS is investigated. Results show that acute angles have a better SERS effect, and the smaller the angle is, the more obvious the effect will be. Dependence on angle of SERS decreases in the case of obtuse angle.

The feasibility of real-time monitoring on biological tissue laser thermal damage based on visible and near-infrared spectroscopy is investigated. Thermal damage experiment is carried out in fresh porcine livers with laser of 5 W, 808 nm. Visible and near-infrared spectra (330～1100 nm) are acquired in real time at distances of 4, 8, 12 mm from the damage center, and the diffused light intensity at 720 nm (R d 720)is chosen as the evaluation factor. Results show that R d 720 increases quickly with the increasing of tissue temperature in the initial stage of heating. The smaller the distance between the spectral measurement point and damage center is, the faster R d 720 will increase. After reaching the effective damage, temperature continues to rise while R d 720 tends to be stable if keeping heating. After the heating is stopped, the tissue temperature gradually returns to room temperature, while R d 720 decreases slightly and remains almost a constant which is far higher than its initial value. It can be found that the visible and near-infrared scattering intensity of biological tissue can be used as an important parameter to real-time monitoring laser thermal damage.

Catadioptric null compensation test is a novel concave aspheric mirror testing method which combines the advantages of Offner refractive and Maksutov reflective compensation test. Its compensation ability is strong and testing optical path is compact. Non-spherical test with large aperture and large relative aperture is a difficult problem to restrict the improvement of its processing quality. In view of a concave paraboloidal reflector whose aperture is 4 m, eccentricity ratio is 1, and vertex curvature radius is 16 m, a catadioptric null compensator is designed. Based on the third-order aberration theory, the arrangement and calculation of the compensator initial structure is carried out. The initial structure parameters are optimized with Zemax, and the finial structure of compensator is obtained. The axial size of testing optical path is about 12 m. The residual wave phase error is 0.005λ after system optimization. The design and simulation results show that the catadioptric null compensator is very advantageous for the processing and testing of large aperture concave aspheric mirrors.

An algorithm to improve the brightness uniformity of LED display screen is proposed based on display screen control technology and correction principle. The charge-coupled device (CCD) camera is used to collect the RGB images of display screen. The position of LED light is determined by using mathematical morphology and template matching method. The relative brightness of light emitting region is calculated according to grayscale value of light emitting region. The correction parameters of each light point are generated and pulse width modulation is used to control brightness of light points. Experimental results show that the proposed algorithm can effectively improve the brightness uniformity on LED display screen, and its display quality and prolong its service life.

The image fusion method based on contrast pyramid decomposition has good physical meaning, but there is no emphasis on direction. An image fusion method based on directional contrast pyramid decomposition is proposed. The contrast pyramid decomposition of multi-focus images is performed. Multiple directional sub-images are obtained for each high frequency image by using directional filter banks. According to the characteristics of different frequency domain, the decomposed sub-images are fused, and the fusion rule is that the weighted average value is selected for low frequency sub-band coefficients, while for high frequency sub-band coefficients, the coefficients with larger absolute value are employed. Results show that the fused images obtained by the proposed method have high definition and spatial resolution. Compared to the fusion methods based on the contrast pyramid (CP) decomposition and discrete wavelet transform (DWT), the proposed method can not only keep the meaning of contrast, but also provide 2n direction information.

In order to reduce noise influence and improve false contour phenomenon caused by automobile body reflection, a new contour extraction algorithm combining visual neurons dual antagonism mechanism and adaptive dual threshold is proposed. Original images are processed by dual antagonism mechanism algorithm to get contours of brightness characteristics according to visual neurons dual antagonism principle. High and low threshold values are selected automatically according to brightness distribution of the contours by using extended Otsu algorithm. Double threshold processing is carried out to the contour preliminary extracted, and the final automobile contour is obtained. The objective performance index is used to evaluate the experimental results. Results show that the proposed algorithm improves the integrity of automobile contour. Compared with the classic contour extraction algorithm, it has low computing complexity and good adaptability of image background.

In order to realize the synchronous secure encryption of two plains, a double image encryption algorithm based on the combination of discrete multi-parameters fractional angle transform and low dimension mapping is proposed. The composite coefficient matrix model is constructed based on discrete cosine transform (DCT) and Zigzag scanning, and the two plains are merged into an image by using inverse discrete cosine transform (IDCT). The initial condition values are calculated by using mean value of the plain pixel and external key with the coupled Logistic mapping, and two random sequences are outputted by iterating this coupling map. The position array disrupt mechanism is constructed by sorting two random sequences for scrambling compound plain. The scrambling cipher is decomposed into two new components, and the two new components are fused into temporary cipher by combining the chaotic random phase mask generated by logistic map with modulated phase mask. A new 2D multi-parameter fractional angle transform is constructedbased on discrete fractional angle transform. The encryption model is designed and image encryption is completed. Results show that the proposed algorithm is more secure than the existing dual image encryption schemes, and has better anti-plaintext attack characteristics.

In order to suppress the long-term frequency drift of CW lasers, continuous laser modulation-free frequency stabilization can be realized by computer control with precision wavelength meter as reference frequency standard. The method obtains the wavelength meter data from computer, and the feedback voltage value output to laser is calculated by using digital proportion-integral-derivative (PID). Thus the laser cavity length is modified, and the laser frequency is locked. This method can be applied to any given wavelength within spectral range of a commercially available laser, and can lock the laser to any absolute frequency within its tunable frequency range. The locking of 631 nm external cavity semiconductor laser is achieved with this method, and the stable locking with frequency uncertainty of 7.4 MHz for an hour, long-term frequency drift rate of ±1.1 MHz/h is obtained.

A set of three wavelength Nd:YAG laser system with high stability and high energy output is designed, which is used as laser cleaning source. The system includes an oscillator, an amplifier and subsequent wavelength switching system. In order to solve the output energy decreasing and instability caused by thermal birefringence effect of the laser rod, a quarter wave plate is inserted between the output mirror and laser medium, and the compensation effects of the waveplate are investigated. Results show that output energy of the oscillator increases by 10% and the stability is improved obviously after inserting the waveplate. When the repetition frequency is 10 Hz, the single pulse energy of 1064 nm laser after amplificating reaches 700 mJ. It passes through the frequency doubling crystal BBO, and 325.6 mJ single pulse energy of 532 nm laser is obtained. The single pulse energy of 266 nm laser is 84 mJ after fourth harmonic generation. Three wavelength laser output energy instability is less than 0.6% in one hour.

The real orbital movement of satellite has an impact on the satellite-ground quantum communication experiment. The change of satellite-ground distance leads to the change of signal time interval, and thus it affects time synchronization in quantum communication, reduces final key rate and even fails to generate keys. The satellite-ground quantum communication data can be simulated by using the fixed-point quantum communication data, which can be used to detect the time synchronization performance of satellite signals at different orbital heights before satellite launch. By analyzing the time synchronous scheme, the signal light receiving end time variation which reflects the distance change is simulated. The practical data of satellite-ground quantum communication experiment are used to verify the simulation model, and results show that the model matching degree is good.

In order to improve the overall performance of measurement-device-independent quantum key distribution (MDI-QKD), the properties of photon number distribution can be optimized by using the modified coherent source (MCS), and a MDI-QKD system is designed based on MCS. The relationship between key generation rate and transmission distance is derived based on calculation method of global estimation. The full use of single photon information during privacy amplification calculation stage is ensured, and the more accurate lower limit value of key rate is obtained. The performances of proposed system and MDI-QKD system based on heralded single photon source (HSPS) are compared by simulation analysis. Results show that the transmission distance of MCS light source is increased by 9% than that of HSPS light source, and the system performance is improved effectively.

Electromagnetic induced transparency, optical pulse deceleration and storage in rubidium atomic vapor are realized based on laser sideband injection method. In order to realize the coherent manipulation of rubidium atoms, the output of master laser is locked on the F=1→F′=2 transition of D1 line of 87Rb atoms. After modulated by an electro-optic modulator (EOM) with frequency of 6.8 GHz, the negative first frequency sideband generates resonance with the transition frequency of F=2→F′=2 transition of D1 line. The negative first frequency sideband is injected into the locked slave laser, and the two output beams of the master and slave lasers are two-photon resonant with the two hyperfine energy levels of the ground state of rubidium atom, which can be used to coherently manipulate rubidium atoms. The two output beams of the master and slave lasers can be input into a rubidium vapor cell, as the probe and coupling lights, respectively. Electromagnetic induced transparency, deceleration and storage of optical pulse can be obtained by manipulating the waveform and switch of the two beam.

In order to realize the more economical probability teleportation of four particle cluster state, a teleportation scheme using five particle cluster state as quantum channel is proposed. Based on the disentanglement-teleportation-reconstruction method, the sender does a CNOT operation and projection measurement on information state before sending information. The disentanglement information is sent to the receiver. In this process, the sender needs to carry out two Bell state and single particle measurements. The receiver carries out the corresponding operation according to the sender’s measurement results, and the entanglement information state is obtained. The original unknown information state is reconstructed by introducing auxiliary particle, and the probability of information successful transmission is 4|a|2. The scheme can be a good way to deal with the general eavesdropping.

Different entangled states are usually required for realization of different quantum information processes. A special five-particle entangled state was proved to be used in several quantum information processes such as quantum teleportation, quantum state sharing and quantum dense coding. Based on cavity quantum electrodynamics, a preparation scheme of the special five-particle entangled state is proposed. The atoms and cavity field are chosen in a certain initial state. Multiple atoms interact with each other in cavity field and the interaction time is selected. By means of the classical unitary transformation, the five atoms are prepared in a special entangled state. There is no energy exchange between the atoms and cavity field during the whole preparation process, and no quantum measurement is needed, which makes the scheme more easily implemented in experiment.

In order to apply a powerful neural network to the continuous-variable quantum information processing, it is necessary to construct the continuous-variable quantum neural network (QNN) model. Coherent state quantum logic gates are taken as basic elements. Quantum circuit composed of input layer, hidden layer and output layer is constructed based on QNN principle, and the function of continuous-variable coherent state quantum neural network (CSQNN) is realized. The model realizes quantum state operation by using multi-bit CNOT gate, and the learning training of network parameters is completed by using phase rotation gates. Simulation results show that under the assistance of CSQNN, the quantum teleportation fidelity of amplitude damping channel with damping coefficient of 0.5 is significantly improved, and its value approaches 1. It’s shown that the proposed CSQNN model can effectively deal with the continuous-variable quantum information.

The interaction between a two-level atom trapped in symmetric double-well potential and a single mode cavity field is investigated. By solving Schrdinger equation, the analytical expressions of the total wave function and inversion of the atomic energy level for the whole system are given. Time evolution of the atomic population inversion is analyzed for different initial states of the cavity field, such as particle number, coherent and thermal states. Influence of atomic mass centre motion on population inversion is considered. Results show that by choosing appropriate cavity field initial state, potential well location and related factors, the spontaneous emission rate of an atom can be effectively controlled.

The band gap structure of one-dimensional photonic crystals is investigated using the transfer matrix method. When the width of medium layer is changed, the band gap will be changed accordingly. Numerical analysis results show that continuous and larger band gaps can be obtained by combination of different thickness of medium layers. By using this method, the ideal filtering effect can be obtained without changing the total medium thickness of photonic crystal materials.

A compact ship-borne Mie scattering lidar system is developed which can continuously observe vertical distribution of marine atmospheric aerosol optical properties, and marine atmospheric aerosol observation experiments are carried out in the offshore area of Qingdao, China in May and September, 2015, respectively. The aerosol optical depth (AOD) obtained synchronously from a handheld Microtops II sun photometer on board is used as comparison data, and AOD measurement results of the two instruments are compared. The average laser radar ratio, standard deviation of the observed offshore area is 32.4 sr, 4.6 sr, respectively. The aerosol extinction coefficient profiles below 15 km at the experiment area in summer are retrieved by Fernald method. The continuous observation experiments show that the developed ship-borne Mie scattering lidar has compact structure, and is easy to operate on a ship-borne platform. It can measure continuously and effectively the high spatial and temporal resolution profiles of optical properties of the offshore atmospheric aerosol.

In order to preliminarily investigate the feasibility of nickel electroplated Co-pellets working in non-neutron irradiated steady state pressurized water reactor and influence of extreme accident on electroplated nickel coating, the nickel plated Co-pellets are heat treated at 400 °C, 600 °C in 2 MPa helium environment for 240 h, 0.5 h, respectively. The surface and fracture morphology of the electroplating nickel layer are characterized by scanning electron microscope. The diffusion of interface elements between coating and substrate is analyzed with energy dispersive spectrometer. Results show that the abrupt change of thermal expansion coefficient near Curie temperature 358 °C of nickel layer and the phase transition of cobalt near 427 °C will not cause destructive damage to nickel coating. The element inter-diffusion of interface makes the combining of coating and substrate more closely.

In order to solve the problems of low channel transfer efficiency, high bandwidth utilization and difficult to improve data transmission quality in the current LTE network data transmission optimization algorithm, a new LTE network data transmission optimization algorithm is proposed. Based on time division multiple access (TDMA) control technology, the channel bandwidth offset is optimized combining with Markoff channel transfer model. The ups and downs tracking mechanism is constructed by obtaining channel transition probability of excited state and non-excited state, and the fluctuation characteristics in channel transfer are selected. Simulation results show that the proposed algorithm has the lowest bandwidth required for data transmission, higher data transmission quality and better channel transmission performance compared with the hybrid carrier band-pass and narrowband noise adjustment adaptive filtering algorithm in the current LTE network data transmission.

A new type of metal-insulator-semiconductor (MIS) hybrid surface plasmonstructure is proposed. It is verified that the structure has obvious TM mode band gap in the normalized frequency range of (0.243～0.271)a/λ. Line defect is formed by removing and changing the radius of air holes in the two-dimensional photonic crystal layer, and hybrid waveguide structure 1 and 2 are constituted. Analysis shows that the photon energy whose frequency is located in the bandgap is well confined in the low index layer and can only be transmitted along the line defect. When the incident wavelength is 1550 nm, the transmission distances of two waveguides are 18.41 μm, 15.70 μm, the group velocity extreme values are 0.186c, 0.166c, the quality factors are 384.74, 1042.50, respectively. The waveguide can control the transmission path of low refractive index layer surface plasmon polariton (SPP) through the line defect of photonic crystal layer. It provides an effective theoretical basis for the research of waveguide devices.