Because of its high detection accuracy, fast response time and compact system structure, coherent lidar has made great progress in the field of wind measurement and has become one of the most advanced wind measurement tools in recent years. It′s shown that coherent lidar has good research significance and application prospects. The technical advantages of coherent wind measuring lidar are briefly introduced, and two kinds of coherent wind radars using continuous wave laser and pulsed laser as light source respectively are described in detail. The development history and the latest progress of these two technologies at home and abroad are mainly focused, and at last the development trend of coherent wind measuring lidar is summarized from the choice of light source wavelength, the way of laser working and the diversity of application platform.

Graphene plasmons have tremendous potential applications in middle-infrared to terahertz frequencies. Previous studies mainly focused on the coupling between graphene plasmon and phonon of substrate, while the approach to modulate such coupling has been rarely reported. One possible approach to modulate such coupling is to change the dielectric environment around graphene nanoribbons (GNRs). Numerical simulation indicates that compared with GNRs on flat SiO2 substrate, GNRs in grooves demonstrate stronger coupling between plasmon and phonon. In addition, the dispersion curve of plasmons shifts down when the frequency is away from the frequency of phonon, and the maximum absorption of the two dispersion curve branches at low frequency is also significantly improved. On the contrary, GNRs on the SiO2 protruding platform lead to contrary results. Such observations reveal that the coupling between graphene plasmon and phonon of substrate can be efficiently modulated by simply changing the edge dielectric environment of GNRs.

CN radical plays an important role in the process of life formation. The generation of CN is closely related to nitrogen(N2) and methane(CH4) in the early planetary atmosphere. Considering the atmospheric compositions of Titan, N2 and CH4 are mixed to simulate the early atmospheric environment, then the simulated atmosphere is discharged to generate CN. The influence of CH4 to N2 ratio and the trace gases in Titan atmosphere on the generation of CN are studied by measuring the absorption spectrum of CN radicals. It is shown that, under the low-pressure glow discharge of N2 and CH4 mixture, the concentration of CN radicals is the largest when the CH4 gas pressure accounts for about 20% of the total gas pressure. When the pressure ratio of N2 and CH4 is kept constant, the concentration of CN radicals increases with the increase of total pressure at first. When the total pressure reaches 60 Pa, the concentration of CN radicals will slow down with the increase of total pressure, and when the total pressure is more than 90 Pa, the concentration of CN radicals starts to decrease slowly with the increase of total pressure. Given the gas pressure and the CH4 to N2 concentration ratio, the concentration of CN radicals increases with the increase of discharge current. It is well known that there are trace amounts of water vapor (H2O), carbon dioxide (CO2) and carbon monoxide (CO) in Titan atmosphere, and it is found that the addition of a small amount of these gases in the discharge of N2 and CH4 mixture will suppress the formation of CN radicals.

In order to obtain high-intensity water window spectral continuum, a method to control the laser waveform by using frequency-chirp field is proposed. It is found that the harmonic cutoff can be extended in the presence of single-color multi-cycle negative chirped pulse. With the introduction of the second negative chirped pulse, not only the harmonic cutoff can be extended to the water window region, but also the harmonic yield can be enhanced by nearly three orders of magnitudes. When the third 123 nm ultraviolet pulse is added, the harmonic yield can be further improved due to ultraviolet resonance ionization, and the enhancement of harmonic yield is nearly independent of the chirp and laser phase of the third pulse. Finally, with the superposition of the harmonics on the water window spectral continuum, a 38 as pulse can be obtained.

The whole assembly of the range-gated imaging system based on the semiconductor laser array is introduced, and three kinds of semiconductor laser beam shaping designs are proposed according to the requirements of the system. The simulation and experimental comparative analysis of the three laser beam shaping designs are carried out by using Zemax software. Results show that the stacked array macro lens collimator has the advantages of simple structure, low assembly accuracy and low cost, but it requires high parallelism and coplanarity between bars. The collimation scheme of optical fiber coupling array has the smallest beam divergence angle, but larger coupling loss. The beam shaping scheme of the stacked array based on cylindrical microlens has a high light collection efficiency, a smaller divergence angle and moderate process complexity, which is more suitable for the long-distance active lighting of the laser imaging system engineering.

The optical transmission characteristics in a ring cavity optomechanical system with two special paths are investigated. The structures of the two paths are independent of each other, but there are phonon and photon couplings between them. By adjusting the coupling intensity and the effective optomechanical coupling rate of the two independent coupling paths, the system shows the tunability of induced transparency. When the coupling intensity is large, the transparent peak of symmetric detuning point will be produced. And the distance and intensity of the transparent peak can be regulated by coupling intensity of the two paths, which makes the all-optical switching based on the system feasible in theory. In addition, the group delay of transmitted light can be easily changed by adjusting the relevant parameters, and the tunability of fast and slow light can be realized by many ways. Under some conditions, the system shows the excellent characteristics of fast and slow light modulation, which will provide a good platform for the fabrication of related photonic devices and the research of quantum phenomena.

A round-robin differential-phase-shift quantum-key-distribution (QKD) protocol without three-photon pulses is proposed. This protocol can generate a secure key without monitoring signal disturbance, thus effectively reducing the complexity of implementation. Moreover, two kinds of intensity decoy states are applied to estimate the key rate in the proposed protocol. The results show that the key rate of the proposed protocol is significantly improved, and the corresponding maximum transmission distance is also increased. In addition, as only two-intensity decoy states are needed to achieve the same performance as infinite decoy states in the proposed protocol, the consumption of decoy states are effectively reduced.

A theoretical scheme for asymmetric bidirectional remote preparation is proposed by using a special quantum channel with one cluster state and three Bell states entangled together. In this scheme, Alice and Bob are both senders and receivers of remote quantum information. Alice helps Bob to prepare a three-qubit entangled state remotely. Meanwhile, Bob also helps Alice to prepare a four-qubit cluster state remotely. Alice and Bob use the orthogonal measurement basis matched with the quantum channel to measure the projection of the qubits (1, 3, 5) and (8, b). After receiving the measurement result of the other party, the receiver carries out unitary transformation operation corresponding to the measurement basis for each measurement result, and the probability of direct and successful preparation is 1/8. Then, the method to improve the probability of successful preparation is given, in which a specific coefficient is selected firstly, then the above operation is repeated to complete the asymmetric bidirectional remote preparation of an arbitrary three-qubit entangled state and a four-qubit cluster state. After calculation and verification, the probability of successful preparation is up to 100%, and the information transmission efficiency of the system is 36.84%.

Two schemes for deterministic remotely preparing an arbitrary two-qubit state with complex coefficients using Bell states as the quantum channel are proposed. In the first scheme, the sender can help either one of the two receivers to remotely prepare the original state with the appropriate probability. And in this process, the sender needs to perform three-particle projective measurement and the controller needs to perform Hadamard gate operation. In the second scheme, two senders independently share the classical knowledge of a quantum state, and the receiver can reconstruct the original state if and only if all the senders collaborate with each other. The four-particle projective measurement is needed in this process. It is shown that the total successful probability of each scheme can reach 1. Moreover, the quantum resource in the two schemes is only the simplest entangled Bell state, and the whole operation process is simple and flexible.

Key expansion is an efficient way for quantum noise random stream cipher (QNRC) to use quantum key distribution (QKD) keys. Generally, the classical encryption methods are often used for key expansion in QNRC experiments, such as advanced encryption standard (AES) and Hash algorithms, because of the difficulty of deciphering. According to the working mode of block cipher, the Hash expansion schemes of counter (CTR) mode and cipher block link (CBC) mode are reasonably designed. Moreover, NIST random test is implemented on the running key streams generated under different expansion schemes. The test results show that AES and Hash expansion schemes both in CTR and CBC modes can pass the test of randomicity. Especially for the Hash expansion in CTR mode, the input length of which can be flexibly controlled, so it can better adapt to different requirements of modern high-speed optical network.

Deutsch-Jozsa algorithm realizes the exponential acceleration of classical algorithm for the first time, and solves the Deutsch problem of n qubits. The algorithm establishes the basic idea of quantum algorithms, and the implementation of which embodies the characteristics of quantum superposition and parallelism. A comprehensive algorithm is proposed for the first time, which can automatically generate all eight truth tables and quantum circuits of two-bit Deutsch-Jozsa algorithm. A synthesis method is given further to judge the properties of f(x) by constructing quantum circuit when the corresponding circuit is unknown. Generally, to solve this problem, a typical classical algorithm needs to do 2n+1+1 times of judgement and the Deutsch-Jozsa algorithm only needs one time. Although the new approach requires two steps to solve the problem, it provides another possible way to solve the problems with specific requirements in practical application. In addition, the correctness of the quantum circuits and Deutsch-Jozsa algorithm is verified by IBM Q Experience platform.

The monogamy of entanglement is an important property in quantum entanglement, which can be used to characterize the entanglement structure in multipartite systems. Tsallis-q entropy entanglement is a well-known entanglement measure, and the squared Tsallis-q entropy entanglement obeys a monogamy relation with 5－132≤q≤5+132. A new entanglement monogamy relation is presented when the μ-th power of Tsallis-q entropy entanglement with 5－132≤q≤5+132 is satisfied with μ≥2. It is shown that this monogamy relation is more strict than the monogamy relation of squared Tsallis-q entropy entanglement proposed by Song et al.

Based on the Von Neumann quantum reduced entropy theory, the evolution properties of field quantum entropy in the interaction system of Λ-type three-level atom and single-model field are investigated when the coupling between the field and the atom changes with time and intensity under the on-resonance condition. The influences of the different initial fields and changes of the coupling coefficient on field quantum entropy is discussed in detail through numerical calculation. Results show that the different statistical properties of the initial fields will lead to the great variation of the field quantum entropy, and the changes of the coupling strength modulation function will change the oscillating frequency of the field quantum entropy evolution. In addition, it is shown that the initial stage of the interaction between the field and atom is a gradually coupled procedure, and the superposition state probability of the atom makes the field quantum entropy change periodically.

An efficient method for generating unitary matrix of quantum logic circuits is presented. First, the truth table is generated by using the operation rules of quantum gates in the quantum circuit, and then the unitary matrix of the quantum circuit is constructed according to the mapping relationship between the truth table and the unitary matrix. Traditional methods are to generate a matrix by using the topological transformation rules of quantum gates, and then multiply the matrix of quantum gates in the quantum circuit to construct a quantum circuit. When the quantum circuit is large, traditional methods involve the generation and product of many large matrices, which results in a huge time cost. The method proposed here achieves dimensionality reduction skillfully, which greatly improves the efficiency of the algorithm. Taking GT circuit and NCV circuit as examples, when the number of quantum lines is as high as 8 and the number of gates is 643, the speed of the proposed method is hundreds of thousands of times faster than that of the previous methods.

The spectral emissivity and temperature of the Dunhuang site, China, are important parameters for on-orbit radiometric calibration in thermal infrared band of satellite remote sensor based on the Dunhuang radiometric calibration test-site. In August 2018, the surface spectral emissivity of Dunhuang radiometric calibration test-site were measured repeatedly under different time and observation conditions using a portable Fourier transform infrared spectrometer (D&P 102F) and an infrared standard plate. Based on the iterative spectrally smooth temperature and emissivity separation algorithm (ISSTES), the spectral emissivity and temperature of Dunhuang site are separated by setting the temperature difference interval with different precisions and performing multiple iterative smoothing analysis on the measured field spectral data. Compared with the emissivity of CE312 channel obtained by multi-channel temperature and emissivity separation algorithm, the results show that the deviation of emissivity of each channel is within 0.011, which verifies the spectral emissivity and temperature of Dunhuang site obtained in this work have better accuracy. This experiment provides a reference for the on-orbit radiation calibration of satellite remote sensors based on the Dunhuang calibration field.

Space-borne cloud-aerosol lidar can accurately obtain global cloud-aerosol detection data. Using narrow-band filter of interferometer to detect clouds and aerosols in the atmosphere can improve the signal-to-noise ratio of echo signals, and make all-day detection possible. According to the requirements of application environment and temperature tuning of spaceborne lidar, a solid-etalon is selected to realize the interferometer filter, and the material selection and structural design of which are analyzed. Furthermore, the temperature-controlled structure is added during packaging, and thermal stress coupling analysis is performed on the solid etalon. Considering the influence of operating temperature and incident angle, the optimal performance test scheme is given. It is found that the temperature tuning of the solid-etalon measured according to the scheme meets the central wavelength tuning range.

Forward error correction is the key technology to ensure the reliability of data transmission in 25 G-EPON system. For 25 G-EPON system, random errors and continuous burst errors often occur in the process of data transmission due to the high transmission. By analyzing the RS coding and decoding algorithm and selecting the appropriate RS characteristic parameters, the influence of these parameters on the transmission performance of 25 G-EPON system is simulated and analyzed. Then the appropriate RS code scheme is chosen for 25 G-EPON communication system. The experimental results show that under the premise of satisfying the reliability of the 25 G-EPON system, the coding efficiency should be reduced as much as possible, the redundancy of coding should be improved and the coding scheme with shorter code length should be adopted, so as to improve the coding gain of the RS code and reduce the bit error rate of information transmission. It is shown that RS (1023, 847) code can correct up to 880 bits errors consecutively, and the coding gain can reach 8.834 dB when the symbol error rate reaches 10－12, which can meet the transmission requirements of 25 G-EPON system. Therefore, RS(1023, 847) code is selected as the forward error correction code of 25 G-EPON system.

In order to realize a multipurpose integrated optical device, a power splitter with tunable splitting ratio is designed based on the modulation function of graphene-silicon waveguide. In the splitter, graphene layers are embedded in the waveguide of one arm of the Mach-Zehnder(MZ) structure, and an extra phase difference is introduced by applying bias voltage to obtain output power modulation. The finite-difference time-domain (FDTD) method is used to calculate the properties of the graphene-silicon waveguide, and then the transmission performance of the splitter is simulated. Both theoretical and simulation results show that the designed splitter has good optical performance, and its splitting ratio can be tuned by bias voltage.