The evolution properties of quantum entanglement in a system of multimode coherent field interacting with two identical two-level atoms through degenerating multi-photon process are investigated using the Von Neumann quantum reduced entropy theory, and the analytical expression of quantum entanglement and the numerical calculation results for two-mode field interacting with the atoms are obtained. The results show that: the quantum entanglement will strengthen with the enhancement of the photon degeneracy; the periodicity of the quantum entanglement will become more and more apparent with the increasing of the average photon number; when the field and the atoms are far from resonance, the quantum entanglement will decrease with the increase of the frequency detuning; when the frequency detuning is large enough, the field and the atoms are nearly always in entangled states. These results are useful for the preparation of the entangled states or pure states and for quantum information in optics systems.

Qudit quantum system can carry more information than that of qubit, so it is an important resource in quantum information processing. The ququart state with the tensor representation is gotten in term of the photon entangled state. The necessary and sufficient condition for realizing a successful or perfect teleportation is obtained, as will be shown, this condition is determined by the measurement matrix and the quantum channel parameter matrix. The general expressions of the measurement matrix are written out and the quantum channel parameter matrix are discussed. Furthermore, the teleportation of ququart state is proposed via different kinds of quantum channels. The description of the teleporting process with the help of tensor analysis is more compact and clear.

With the constant expansion of the optical networking and network architecture flattening process accelerated, network transmission reliability and timeliness are facing new challenges, which brought a new challenge to the survivability routing algorithm. In order to realize dynamic survivable mapping of IP routing to WDM based optical networks, with strong robustness and memory capacity of the ant colony optimization algorithm, a novel pheromone structure and pheromone update mechanism is proposed and survivable constraint information is also introduced to improve the probability mechanism of routing selection. The survivable mapping considers the cut sets of all single node and the dynamic characteristics of the IP over WDM network. Compared with other similar algorithm, the algorithm is no longer an alternate route set and the physical topology of the storage network itself huge cut-set relationship, under the premise of ensuring network survivability effect by cut-set relaxation conditions effectively reduce the computation time complexity to improve the convergence rate to adapt to the real-time requirements of the network. Simulation results show that the proposed algorithm can effectively improve the performance of survivable mapping, network resource utilization efficiency and the blocking rate compared with the shortest path algorithm.

In order to eliminate the influence of the F-P filter temperature characteristics on the accuracy of the fiber Bragg grating wavelength demodulation system, a method is put forward that uses the F-P etalon as a wavelength reference to calculate the wavelength. A high precision fiber Bragg grating wavelength demodulation system is designed, and the algorithms for filtering, peak detecting and wavelength calculating are achieved by LabWindows/CVI. The experimental results show that the repeatability error is smaller than 1.56 pm, and the stability error is smaller than 1.13 pm.

The modal properties of large-mode-area microstructured optical fiber with two-ring holes are analyzed. By using the multipole method and finite element method, the influence of inner and out hole sizes on the fundamental mode and higher-order mode losses of the fiber are numerically calculated and analyzed. In addition, a large-mode area microstructured optical fiber is designed with high loss ratio of higher-order mode and fundmental mode as well as allowing for bending at a moderate radius. For the fiber with the inner ring of hole diameters of 34 μm and the outer ring of hole diameters of 24 μm, the fundamental mode loss is 0.000 17 dB/m, whereas the high order mode loss is 1.39 dB/m. The mode area of the fundamental mode is 2 150.9 μm2, and the bending loss at the bending radius of 1.2 m is 0.106 dB/m.

The uncertainty of ozone differential absorption lidar (DIAL) measurements due to the effect of background noise is presented. The effect of background noise on ozone concentration profiles is proportional to the background intensity and the ratio of return signal intensities at “on” and “off” wavelength. Analysis suggests that an appropriate return signal intensity ratio can make the effect of background signal very small, negligible. The simulations based on the analysis coincide with the experimental results.The experimental results show that the impact of background signal is negligible at an appropriate return signal intensity ratio of 0.96 at wavelength pair (280 nm,285 nm). In case of unknown background intensity, we can adjust the laser pulse energy levels at the two wavelengths to obtain an appropriate return signal intensity ratio on the oscilloscope to suppress the impact of background signal and ensure the accuracy of night time ozone measurements.

Scattering effects of clouds and fogs produce the backscattering signal which results in false alarm for laser fuse. Based on the Monte-Carlo technology, cloud-and-fog scattering effects are simulated, and rules of wave shape and peak power of cloud-and-fog scattering echo variable with baseline distance are qualitively given. Results show that peak power and pulse broadening extent of the laser echo goes up with pulse width increasing. However, when pulse width increases to 50 ns, peak power is saturated. Simulated results may provide target discrimination and optimized design of detecting threshold and transmitting pulse width for laser fuse with reference.

Atmospheric aerosols is a key element of climate changes and air pollution, the analysis of the aerosol optical and physical properties can reduce uncertainties in the quantitative assessment of aerosol effects on regional climate and environmental changes, especially in the mega-city. In this study, from December 2010 to August 2011, in situ measurements of aerosol optical properties were conducted at rural and city sites of the mega-city Shenzhen in southeast China. The aerosol optical depth showed a seasonal cycle with the lowest values in summer, while the highest values occurred in winter and spring. The annual cycle of Angstrom wavelength exponent showed a summer minimum associated with sulfate aerosols, and a spring/winter maximum associated with heavy air pollution. The scatter grams of the optical thickness and Angstrom wavelength exponent also indicates that the high aerosol optical thickness mainly come from the city pollution. Mean values (standard deviation, S.D.) of scattering and absorption coefficients for the entire period are 178.7×10-6 m-1(126.6×10-6 m-1) and 32.5×10-6 m-1(18.1×10-6 m-1) respectively. These values are approximately half of the reported values obtained in the Guangzhou urban area. The mean single scattering albedo for the entire period was estimated as 0.81, which is similar to the values reported for the other urban area. The daily variations of aerosol absorption and scattering coefficients were strongly influenced by synoptic changes throughout the observation period.

The characteristics of multi-alkali photocathode and its application in low light level image intensifier are introduced, the principle of light induced fluorescence is described, the method to study electron transition probability of Na2KSb cathode film by use of light induced fluorescence is explored, and the fluorescence spectrum of two different cathodes in the states of work and non work are measured respectively. The test results show that, the fluorescence intensity of cathode is proportional to both its electronic transition probability and sensitivity, at the same time fluorescence intensity in work states declines compared to that in non work states. The reason is that part of the transition electrons escape from cathode surface and produce photoelectric emission. These transition electrons do not return to the ground state, therefore they do not emit fluorescence no longer. In this paper the fluorescence spectrum of cathode is also measured excited at different wavelengths of incident light. The results show that, compared with short waves excitation, long waves excitation can obtain higher intensity, which shows long waves excitation can get higher transition electron probability as well; at the same time wavelength shifts between fluorescence peak wavelength and excitation light wavelength is smaller; therefore, the energy loss is small, the photoelectric emission is more favorable. Compared the fluorescence spectrum with multi-alkali photocathode quantum efficiency, it can be concluded that transition electron energy level plays more important role in the process of photoelectric emission between transition electron number and the energy level. As to the multi-alkali cathode, due to electron transition probability of short wave excitation is relatively small, and energy loss of the transition electron diffusion process is bigger, therefore the short-wave quantum efficiency decreases as wavelength decreases. Practice has proved that the photoluminescence is an effective study way of cathode photoemission process, through the study of cathode fluorescence spectrum the cathode photoelectric emission mechanism is further revealed. This provides important reference value for further improving the process and raising the cathode sensitivity.

The 1×2 all-fiber magneto-optic switch with the novel optical route is studied for the all-optical networking, by means of the magneto-optic crystal film, the half-wave plate, the polarized beam splitter, the polarized beam combiner, and the high-speed Faraday rotator etc. Some nanosecond pulse generators are designed and fabricated by the avalanche dynatrons, in order to actuate the miniature solenoid in the Faraday rotator. The dimensions and structure layout of the solenoid are designed optimally, while the magnetic field intensity and the self-inductance coefficient are analyzed to enhance the switching-speed of the magneto-optic switch. The performance measurement results state that the rising-time of the nanosecond pulse is 2~5 ns, the pulse width is 6~12 ns, and the pulse amplitude is 30~150 V. For the all-fiber magneto-optic switch, the insertion loss is 1.55 dB, the crosstalk is 23.69 dB, the extinction ratio is -23.69 dB, and the switching-time is 100~400 ns. The switching-time of the all-fiber magneto-optic switch has reached the nanosecond level.

In order to meet the requirement of tank sight and improve the ability of joint transform correlator in target tracking and recognition, an infrared continuous refractive zoom optical system for 8~12 μm wave-band is designed for 1 inch infrared CCD detector. The zoom system uses mechanical compensation. The relative aperture is invariant during the zoom process. The F number of the system is 2, and the zoom ratio is 4∶1.The focal length from 50 mm to 200 mm could be changed continuously. Variable magnification curve and compensation curve are smooth. The range of tank sight searching targets was expanded. The optical system image quality is evaluated with ZEMAX optical design software. The results have shown when spatial frequency is 17lp/mm, the MTF curve in the whole range of focal length are all above 0.55 which is closed to the diffraction limited curve. The stability of the image plane is well. The result of this system meets the requirement of technical specification.

To meet the requirement of phase-shifting measurement of the wavefront aberration detecting stage for lithographic projection objective, based on theory of Shearing Interferometry, a phase-shifting device is designed. Bridge amplification mechanism is adopted to obtain a larger amplification ratio and a relatively compact structure. The theory of the bridge amplification mechanism was analyzed and discussed, and the functional relationship and its curve between input displacement and amplification ratio were obtained. To make sure the availability of this structure, nonlinear finite element analysis was proceeded. And the results meet the requirements of phase-shifting device of wavefront aberration detecting stage.

In this paper, the concept of “combined array mode” for laser diode bar is proposed, and the far-field profile of “combined array mode” is calculated. The far-field of each combined array mode exhibits a two-lobe profile with different angular position. On the basis of the characteristic of far-field profile of combined array mode, an off-axis external cavity feedback laser diode bar is designed. By employing the setup, the far-field profile of laser diode bar is narrowed by 4.3 times compared with the free-running laser diode bar. The output power of external cavity feedback laser diode bar is about 1.82 W at the drive current of 16 A, or 79% of the radiated power of the free-running state. The theory of combined array mode cannot only be applied to design the external cavity feedback laser diode bar but also can be designed the external cavity feedback laser diode stack.

Multi-wavelength switchable optic fiber laser can select one or several wavelengths of the multi-wavelength. It supports the dynamic allocation of the wavelengths in the optic network, which adapts the development of the wavelength division multiplexing(WDM) and dense wavelength division multiplexing(DWDM) systems with more channel numbers in modern optical fiber communication system. A self-seeded multi-wavelength switchable Erbium-doped fiber laser is proposed and experimentally demonstrated in this paper. The Erbium-doped fiber is pumped by a 980 nm pump to produce 1 550 nm spectra, and it returns back through a ring structure so as to realize the self-excitation and to reduce the cost of the experiment. A Sagnac ring with two segments of polarization maintaining optical fibre is used as a filter. By adjusting the rotation angles of the polarization controller in the circle of Sagnac filter, the cavity gain of the Sagnac filter changes. It allows the wavelengths reflected by the fiber Bragg Grating pass selectively, so as to realize the wavelength switchable function. The experiment proved that it is an effective way to realize the multi-wavelength switchable function through adjusting the cavity gain of the Sagnac Filter and letting the wavelengths pass selectively.

A novel metal-dielectric semiconductor microdisk laser structure with the thickness of 2 micrometer and the radius of 6 micormeter is designed by depositing a silica film and a noble metal gold film on the InGaAsP semiconductor microdisk. The angle between side-wall surface and the bottom plate is 45°. The whispering gallery mode of the device is numerically investigated by using a well-known Finite Element Method (FEM). The so-called weak-form of the partial differential equation is employed to effectively reduce the pseudo-solution associated with the local invariant, which exists in the FEM directly applying to Maxwell equations.The distribution of the cross magnetic field (TM) of the whispering gallery mode of the proposed microdisk laser is achieved based on the numerical solution of the weak-type vector Helmholtz equation. After that the quality factor (Q), the mode volume and other related quantities are discussed. Theoretical results show that the quality factor of the proposed microdisk laser with the sandwich-structure is 2~3 times more than the one with the structure directly deposited metal film in InGaAsP semiconductor microdisk. Furthermore, different thicknesses of the metal and the dielectric quality factor of the microdisk laser and the relationship between the disk radius and the quality factor are discussed. A fundamental mode and higher-order surface plasma wave mode, and a maximum quality factor of about 5 400 optical-dielectric of the fundamental mode are achieved.

In order to realize the function of wavelength division multiplexing(WDM) device with compact structure and high transmittance, a ψ-shape three-channel wavelength division multiplexing device is designed on the triangle lattice photonic crystals which are composed of Si medium columns. Defect modes are produced in the photonic band gap by the introduction of line defects a point defects, the propagation and coupling of light in the photonic crystals are controlled by taking advantage of the defect modes, and the function of solution WDM are thus realized. The band gap and transmission characteristic of the solution WDM were analysed using plane-wave expansion and finite deference time domain method. The parameters of photonic crystal structure with proper defect mode frequency were found and the function of solution WDM with transmittance of 80% was realized.

Based on the method of dispersion characteristics analysis, the Dirac point was found at the center of the Brillion zone in the band structure of the hexagonal lattice photonic crystals, and the phenomenon that both the effective permittivity and permeability approach zero simultaneously at the Dirac point was verified by using the effective medium theory, so that the zero index material can be achieved by the hexagonal lattice photonic crystals at that point. Then, by using the finite element method to perform the numerical simulation, the zero index characteristic presented at or near the Dirac point of the hexagonal lattice photonic crystals was studied. In addition, by designing the concave lens which is made from the hexagonal lattice photonic crystals properly, the results of the sub-wavelength and far-field focusing can be obtained. It is useful to improve the focusing by introducing an antireflection structure to the incident interface of the concave lens, and can improve the effect of focusing and increase the resolution to some extent.

Utilizing a super-luminescent diode (SLD) in 1 330 nm band and a fiber Fabry-Perot tunable filter (FFP-TF), an optical fiber methane sensing system is experimentally demonstrated. The differential absorption technique and a reference method are employed: a reference channel is introduced to eliminate the fluctuation of light source spectrum, and the two wavelengths are acquired by tuning the FFP-TF. The influence of the light source, loss of leading fiber, and the filters′ variations are all avoided. A minimum detectable methane concentration of 0.15% achieved.

A high-sensitive biosensor based on the GMR effect in the self-suspended grating (SSG) is proposed. The calculations demonstrated that the sensitivity of the proposed bio-sensor is near the theoretical limit compared with conventional GMR sensor. Based on the normalized Eigen-function of single layer homogenous grating, the resonance curves with respect to the different refractive indices of surrounding media are calculated, with which confirm the estimated sensitivity. In addition, the highly sensitive bio-sensor in the near and mid IR wavelength region is designed for liquids and gases detection respectively. The sensor can deliver the resolution over 1×10-5 in the near IR region in a large refractive index (1.3~1.7) range and provide better than 1×10-6 in mid IR region, which is enough for various bio-material detections. Therefore, the proposed bio-sensor is one or two order′s more sensitive than the conventional GMR sensors.

A kind of optical fiber MEMS pressure sensor was manufactured by micro electro mechanical systems technology according to the principle of Fabry-Perot cavity interference. A sensitive film which is 6 μm in thickness and 0.502 μm/MPa in mechanical sensitivity was fabricated by adopting the deep boron-diffusion self-stopped etching and magnetron sputtering technique. Based on the intensity-demodulation technology, this kind of pressure sensor makes use of the relation between reflected power and pressure to demodulate the pressure. The study explores the impact of the change of cavity length on reflectance, identifies the light wavelength of linear working point of the pressure sensor, and establishes a stable testing system of fiber Fabry-Perot pressure sensor. The test results show that this kind of sensor has a minimum pressure resolution of 62 Pa and a sensitivity of 0.51 nW/KPa, displaying good linearity, high sensitivity and remarkable repeatability. It can be used to measure the pressure in the human body and the power of the oral denture on the below structure.