Electromagnetic field distribution and resonance modes in Tamm structure are analyzed based on transfer matrix method, and a hybrid aperture-Tamm structure is proposed to enhance the fluorescence signal and control the emission direction. The finite difference time domain (FDTD) method is used to simulate the far field emission of dipole source interacted with hybrid aperture-Tamm structure. It is proved that this structure can realize the vertical ejection of fluorescence and the fluorescence intensity increases by three orders of magnitude compared with the conventional Tamm structure. Influences of fluorescence emission wavelength, position of dipole source, the size and shape of aperture on radiation angle and intensity are systematically analyzed and compared. Simulation results can be used as a guide for the optical chip design with fluorescence enhanced directional radiation function.

In order to improve quality of underwater images, an underwater gray image enhancement method is proposed based on controllable nuclear bilateral filtering Retinex algorithm. An improved Sigmoid function is introduced to enhance the brightness of transformed illumination images, and a bilateral filtering function with controllable kernel function is proposed to estimate the image light intensity, which overcomes edge blurring and halo artifacts problem. Illumination estimation image is corrected by using gain function. Results show that the proposed algorithm accords with human visual characteristics, which can effectively improve the contrast and resolution of underwater images.

In order to solve the problem that the cumulative error caused by model updating on mean shift object tracking becomes larger in the following tracking, a mean shift object tracking method based on four channel non-separable wavelets is presented. Based on the decomposition of target image by non-separable wavelets, the accurate target region is segmented by using high frequency sub-images. The high and low frequency characteristic values of this region are fused, and mean shift tracking is carried out. During tracking, the scale and model updating based on the target contour are used, and the adaptive updating of target feature model is carried out by using correlation coefficient of the sub-features. Results show that the proposed method has both real-time ability and accuracy in tracking the change of scene and target shape. Compared with the tracking methods without image segmentation, the proposed method has better tracking accuracy. Compared with the tracking method using conditional random field (CRF), it has better processing speed and accuracy.

In order to weaken the periodicity of encrypted cipher and improve security and dynamics of the algorithm, an image encryption algorithm based on multi-direction diffusion is proposed. The initial image is divided into two equal blocks, and two random sequences are obtained by introducing Logistic mapping. New arrays are formed by designing quantization mechanism, and they are recombined into two matrices. The pixel cross control strategy is established. Highly confusion of sub-blocks is achieved and the periodicity of scrambling is reduced. The four direction folding encryption method is designed in which each diffusion direction corresponds to a diffusion function for diffusing the pixels form four directions to weaken diffusion periodicity. Results show that proposed algorithm has higher encryption security, anti-attack resistance and privacy compared with the current chaotic encryption techniques, which can improve the ability to resist network attacks of image, and ensure the image information security.

In high power master oscillation power amplification (MOPA) laser, the amplified spontaneous emission (ASE) and induced self-excited oscillation have significant effects on output characteristics of lasers. Relationship between the self-excited oscillation and fiber end surface reflectivity is analyzed theoretically. Based on the self-designed MOPA fiber laser system, relationships between the self-excited oscillation and gain fiber length, pump power, signal power are investigated experimentally. According to the experimental results, the output characteristic curves of MOPA fiber laser are summarized. Results show that when the amplification stage ranges from 10 to 15, the proportion of self-excited oscillation light in output spectrum is the smallest. Experimental results provide a reference for the optimization of MOPA fiber amplifier and improvement of signal to noise ratio of output laser.

Effects of laser pulse width, laser intensity and rotational temperature on molecule alignment of N2O in monochromatic femtosecond laser pulse field are investigated theoretically. Influences of free parameters in laser field on molecule alignment of N2O are investigated in the following three cases. When the rotation temperature and laser intensity keep constant, only the pulse width is changed. When the temperature is constant, only the light intensity is changed at the same pulse width. When the pulse width and laser intensity are unchanged, only the rotational temperature is changed. Results show that by precisely adjusting the pulse width, laser intensity and rotational temperature, the molecular alignment can be enhanced or weakened.

Effects of Bose field environment with an Ohmic spectrum on estimation accuracy of the quantum parameters are investigated based on the typical spin-Boson model. Evolution results of quantum Fisher information of N independent atom systems are obtained by using the two order time-dependent quantum master equation and super operator method. Calculation results show that as the number of entangled atoms increases, the quantum Fisher information increases, and the attenuation of quantum Fisher information is also greatly accelerated. Better measurement accuracy than the standard quantum limit can be obtained in some characteristic period. In the super-Ohmic Bosonic environment with a larger spectral power exponent, the attenuation of Fisher information of quantum entangled state can be suppressed to a certain extent.

A quantum key distribution protocol with two-way identity authentication is proposed based on the entanglement characteristics of Bell states. Compared with traditional quantum key distribution protocol, the proposed protocol has characteristics of zero knowledge, and can carry out two-way authentication. It can simultaneously complete the identity authentication and key distribution with only one time of quantum sequence transmission. Results show that the proposed quantum key distribution protocol can resist the intercept/resend attack, middleman attack and a series of attacks.

The spatial distribution of high-order harmonic generation from H+2 molecules is theoretically investigated. Results show that the molecular harmonic emission mainly occurs around two H nuclei. When the internuclear distance is relatively small, the harmonic intensities of the two H nuclei are almost the same. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus with the internuclear distance increasing. With the introduction of the spatial inhomogeneous laser field, the harmonic intensity emitted by the negative-H nucleus is slightly higher than that of the positive-H nucleus when the internuclear distance of H+2 molecules is relatively small. The harmonic intensity emitted by the positive-H nucleus is higher than that of the negative-H nucleus when the internuclear distance is larger. As the spatial position of the space inhomogeneous laser field shifts from negative to positive(from －100 a.u. to 100 a.u.), the harmonic intensity emitted by the positive-H nucleus decreases gradually. The ultrashort attosecond pulses with durations of 66 as and 62 as can be obtained by superposition of harmonics.

The non-Bohn-Oppenheimer approximation Schrodinger equation is solved numerically. The H+2 molecule harmonic radiation and distribution driven by the spatial inhomogeneous field are investigated theoretically. Results show that when the laser field is positive, the contribution from the negative-H to harmonic radiation is higher than that from the positive-H, and when the laser field is negative, the contribution from the positive-H to harmonic radiation is higher than that from the negative-H. The harmonic cutoff energy increases when the laser spatial position is far away from the origin. When the laser space position is negative, the contribution of negative-H to the higher harmonics decreases obviously. By analyzing the ionization probability, time-frequency analysis of harmonic radiation, the harmonic radiation process is explained by electronic wave packet motion. A 45 as ultrashort pulse can be obtained by superposing harmonics.

The propagation characteristics of Gaussian beam in two-dimensional square lattices and Bessel optical lattices are investigated by alternative implicit differential method. Results show that the lattice solitons with most of energy concentrated in the center can be formed when Gaussian beam propagates in two-dimensional square lattices, and other space discrete solitons can also be formed by adjusting parameters. For Bessel lattice, when the lateral scale is smaller, that is to say, the incident Gaussian beam energy is mainly concentrated in the central channel of Bessel lattice, three-rings-like solitons can be formed with certain applied electric field and photovoltaic field. The single-ring-like and Gaussian-like solitons can be formed with the gradually increasing of crystal lattice transverse scale. The diversity of photorefractive lattice solitons has potential application value in the field of all optical soliton switching.

Spaceborne active differential absorption is a more accurate method to monitor global carbon dioxide. The atmospheric pressure, temperature, humidity, surface reflectivity and the hardware system linewidth, filter bandwidth and so on all have influence on retrieval error. Among them, the surface reflectivity has unnegligible influence on retrieval error. Experimental results show that the spot footprint is smaller, separation distance is bigger, and geomorphology is more complex, the retrieval error will be bigger. When the spot diameter is 100 m and distance interval is 10 m, the absolute error of six geomorphies ranges from 0.0215×10－6 to 0.2134×10－6, which is controlled within 1×10－6. It has certain reference significance to the actual hardware design.

In order to investigate effect of temperature and plasma environment change on charging level of spacecraft surface dielectric materials, the developed surface charging synthetic experimental system for dielectric materials of spacecraft, which is temperature controllable, is used to carry out surface charging experiment of polyimide materials. Results show that when temperature is constant, the surface charging balance potential of polyimide increases gradually with increasing of beam current density, and when the beam density is constant, it decreases gradually with increasing of temperature. When temperature ranges from 243 K to 363 K, the greater the beam density is, the smaller the effect of temperature change on polyimide surface charging balance potential will be. When the temperature ranges from 243 K to 273 K, the greater the beam density is, the greater the effect of temperature change on polyimide surface charge balance potential will be.

MEH-PPV/rGO-CuInS2 hybrid polymer solar cells are fabricated with the graphene/CuInS2 quantum dots hybrid (rGO/CuInS2-QDS) and poly 2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV), and the dynamic characteristics of charge transport are investigated by using dynamic test method. Experimental results show that compared with MEH-PPV/rGO devices, the electron transit time and electron lifetime of MEH-PPV/rGO-CuInS2 devices are significantly increased, which are attributed to the surface defect states trapping on CuInS2 quantum dots and the effective separation of electron-hole pair promoted by CuInS2 quantum dots as a barrier layer, respectively. It is confirmed that the increasing of short circuit current in MEH-PPV/rGO-CuInS2 devices is mainly related to the increasing of exciton dissociation in polymer and decreasing of carrier recombination. The open-circuit voltage of device is mainly determined by the energy difference between the highest occupied molecular orbital (HOMO) level of MEH-PPV and work-function of graphene, and it’s influenced by the electron concentration in graphene.

In order to improve the imaging efficiency and real-time performance of three-dimensional (3D) imaging lidar based on range gating technique, a method to obtain the 3D and intensity information by retrieving the single CCD exposure image is proposed, which is applied to the range gating imaging lidar system. In the proposed method, the echo signal is encoded by sparse sampling matrix, correlation algorithm is used to decode the distance, and the compressed sensing technique is applied to recover the information. The proposed method is investigated by simulation and laboratory imaging experiments, and results show that it can effectively reduce the data amount and improve the system imaging efficiency.

A Y-branch structure which introduces input waveguide, slow-broadening waveguide and wide-transiting waveguide is designed to reduce the insertion loss of optical power splitter. It’s gradually extended to a 1×8 planar waveguide optical power splitter by using OptiBPM software. Effects of waveguide refractivity, arcus waveguide length, branching angle and input wavelength on output performance of the planar waveguide optical power splitter are investigated respectively, and it is optimized by combining the optimal structure parameters. Simulation results show that the insertion loss and optimal value of output uniformity of the splitter are 9.96 dB, 0.41 dB, respectively. The design parameters and performances of device can meet the requirements of mass production, which has certain reference value for the design and production process of optical splitter.

In order to improve the shortcomings of traditional decision threshold technology in free space optical communication (FSO) system and reduce high cost loss caused by that reference light do not carry any information in continuous wave reference light assisted detection technology, an adaptive decision threshold (ADT) technique is proposed that the current code decision threshold is obtained based on the quantized voltage of judged signal previously. The direct current (DC) component in extracted signal is used as continuous wave (CW) reference light to estimate the fluctuating characteristics of atmospheric turbulence channel. Results show that under the condition of bit error rate of 10－3, the adaptive decision threshold and DC extraction technology have lower power loss, which can significantly improve the performance of FSO communication systems.

The physical-layer security of coherent time-spreading optical code division multiple access (OCDMA) system is analyzed quantitatively from the view of security of information theory. Relationships between the system security capacity and different system parameters are obtained. The wiretap channel model of OCDMA system is established, and the system security capacity is calculated. Influences of key system parameters (user number M, input optical power P and code length N) on the physical-layer security of coherent time-spreading OCDMA system are examined by using Gold code as an example. Results show that the coherent time-spreading OCDMA system has a very good physical-layer security against fiber tapping attacks, and the above key system parameters have important influences on improving the system physical-layer security. It can improve the security of coherent time-spreading OCDMA system by choosing the appropriate system parameter values.