With the development of ultra-high capacity optical communication technology, dense wavelength division multiplexing (DWDM) technology is widely used. For DWDM technology, a stable high repetition rate ultrafast pulse laser source is required. If multiple single-wavelength mode-locked lasers are used as signal sources, the cost and complexity of the system will be very high. While dual-wavelength mode-locked laser, due to its advantages of dual-wavelength output, short pulse duration, good beam quality, and wide tunable wavelength range, can overcome the disadvantage of multiple single-wavelength mode-locked lasers, and effectively meet the requirements for ultra-high capacity optical communication technology. In addition, this kind of light source is also widely used in the fields of spectroscopy and microwave generation. Dual-wavelength mode-locked fiber lasers can be realized using dual-resonator structure, high nonlinearity of two-dimensional materials and intra-cavity filtering effect. Specifically, intracavity filtering effect can be introduced by inserting filter devices directly into the laser resonator, using multimode interference or using nonlinear effects such as nonlinear polarization rotation. At present, the output wavelength of dual-wavelength mode-locked fiber lasers is mainly concentrated in the spectral region of 1μm and 1.5 μm band, and the output power is about milliwatt level. In the future, the laser will develop to achieve the output with mid-infrared or even longer wavelength, as well as the average power of watt-level.

The Semi-empirical method was used to study the spectral and dissociation characteristics of dibromochloromethane molecules under the action of external electric field (0-0.040 arb. units) on the AM1 basis set, the influences of external electric field on bond length, dipole moment, total energy, energy level distribution and infrared spectrum were calculated, and the dissociation potential energy curve was obtained. The results show that, when the external electric field increases from 0 arb. units to 0.040 arb. units along the y-axis direction, the bond length of dibromochloromethane molecule is obviously elongated, the molecular dipole moment increases, and the total energy first increases and then decreases. At the same time, with the increase of external electric field, the energy gap decreases, and the infrared spectrum appears red shift or blue shift. In addition, with the increase of applied electric field, the potential barrier decreases and the energy required for dissociation gradually decreases. When the external electric field reaches 0.040 arb. units, the molecule will dissociate. It is shown in this work that the 1C-3Cl bond of is dibromochloromethane molecule is easily broken under the external electric field, which provides a theoretical basis for the degradation of dibromochloromethane.

In order to further improve the research and development of image edge detection algorithm on quantum computer, a quantum image binary morphological edge detection algorithm is proposed combining with quantum computing operation on IBM Q platform. Based on the NEQR quantum binary image representation and quantum binary etching and expansion operations, the corresponding binary morphologic smoothing filtering quantum circuit and edge extraction quantum circuit are designed and implemented. And then through Qiskit extension, the binary morphological edge detection of quantum images with sizes of 8×8 and 128×128 is realized on the virtual local quantum simulator of IBM Q platform. Meanwhile, the comparative simulation experiment of quantum images with a size of 8×8 is also realized on the real cloud quantum simulator of IBM Q platform. The experimental results prove the feasibility and effectiveness of the binary morphological edge detection algorithm for quantum image.

To further verify the validity of the quantum representation of multi-wavelength images (QRMW) model, the quantum states of the QRMW quantum images of with 2×2 sizes and 32×32 sizes respectively were are prepared on QIskit, IBM's quantum computing framework, and a color channel switching operator for QRMW images and a color disarray operator for QRMW images, as well as their implementaiton quantum lines, are proposed.Furthermore, simulation implementation of the newly proposed operator is carried out in the IBM Qiskit environment. The results confirm the feasibility of QRMW model and the feasibility and correctness of the proposed operators.

The suppression of intensity noise in a 1.5 μm distributed Bragg reflector (DBR) single-longitudinal-mode fiber laser using optoelectronic feedback was reported. By analyzing the transfer function from the pump disturbance to the output power fluctuation, it was found that the phase of the fiber laser has a 180° phase mutation at the relaxation oscillation frequency. Therefore, a first-order phase-shifting network, which can provide a 45° lead phase at the relaxation oscillation frequency to compensate for the phase mutation at that frequency, was designed and constructed based on an existing commercial proportional integral (PI) control circuit. With the designed feedback control system, the relaxation oscillation peak of the laser was reduced from -95 dB/Hz to -125 dB/Hz, the suppression amplitude was as high as 30 dB. The suppressed fiber laser is expected to play an important role in applications such as precision measurement.

Tunable semiconductor laser is one of the most important devices in tunable diode laser absorption spectroscopy (TDLAS) system. The stability of the laser output wavelength directly determines the accuracy and stability of system measurements, and the laser output wavelength is mainly controlled by the injection current and operating temperature. A laser drive control circuit is designed, and PID control is utilized to implement thermostatic control of the laser operating temperature. The circuit can not only provide high-precision and low noise injection current, but also have a complete safety protection function for the laser. Firstly, the short-term test and analysis of the injection current and temperature control are carried out. Then, the designed circuit is applied to a laser with a central wavelength of 1512 nm, the temperature and current tuning characteristics of the laser are experimentally test and analyzed, and the stability of the laser output wavelength is tested in both short-term and long-term. The standard deviation of the laser output wavelength is found to be 0.0002, which meets the requirements of TDLAS system for constant current and constant temperature control of laser, and indicates that the designed drive control circuit has realized the high-precision driving control of the semiconductor laser.

Based on the principles of quantum mechanics and the locking algorithm of optical clocks, the generation mechanism of the optical clock output frequency noise is analyzed. Stabilities of single-ion optical clocks was derived from the results of Monte-Carlo simulations and compared with the experimental results. The times of the single ion interrogated by clock laser in each frequency feedback cycle N, and the gain coefficient g, were scanned respectively in simulation to studying the relationship between these parameters and the stabilities of optical clocks. Results show that the 1s stability of the optical clocks is insensitive to N and will degrade when g > 0.45. In addition, compared to the quantum projection noise, stabilities caused by the clock laser's linear drift is negligible. The proposed simulation method of single-ion optical clocks can be easily achieved and applied to evaluate the stability of optical clocks with custom parameters.

The noise of the cold atom gravimeter is analyzed using the sensitivity function analysis method, and then based on the corresponding noise transfer function, a noise transfer model is established and the contribution of vibration noise, Raman optical phase noise and magnetic field noise to the sensitivity of gravity measurement is quantitatively analyzed and evaluated. In addition, based on the correction formulas of Coriolis force and stable platform tilt angle, a system effect analysis model is established, and the influence of heading angle deviation, speed deviation and latitude deviation on the correction of Coriolis force is quantitatively analyzed and evaluated, as well as the influence of the tilt angle deviation on the correction of stable platform tilt angle. Simulation and some measured data show that, on the one hand, when each noise is restricted to a specific level, the influence on the sensitivity of atomic interference can still reach μGal level. On the other hand, 1°heading angle deviation or 0.1 m/s speed deviation can affect the correction of Coriolis force to more than 1 mGal, and 1' tilt angle deviation can also affect the correction of stable platform up to 0.42 mGal, indicating that both effects of noise and system effects cannot be ignored. Therefore, under dynamic conditions, the cold atom gravimeter should undergo noise suppression and system effect correction to obtain high-sensitivity and high-precision gravity measurement results.

Quantum key distribution (QKD) is easy to lose information carriers in channels, so the limited communication distance and key generation rate are the main bottlenecks of its application. Generally, the key rate is limited by the channel transmission rate. The proposed phase-matching quantum key distribution (PM-QKD) protocol overcomes the linear key rate constraint that the secure key rate is proportional to the square root of the transmission rate. Although the PM-QKD protocol can guarantee the security of the detector, there are still some defects in the light source. In the PM-QKD protocol, it is generally assumed that the light source is an ideal coherent state, which is not consistent with the actual QKD system, resulting in some security problems. In this paper, the PM-QKD protocol is discussed under the condition of unknown photon number distribution (UPD), and it's confirmed that the security analysis is still reasonable under the condition of unknown photon number distribution, and it's also shown that the key rate generated by PM-QKD protocol based on light source detection is basically consistent with the key rate under ideal light source.

In quantum key distribution systems, bright light blinding attack makes use of the detection characteristics of linear mode caused by bright light in the actual work of single-photon detectors to control the output of single-photon detectors to be 0 or 1, so as to implement key stealing. To address the potential vulnerabilities of the new type of pulse illumination attack scheme proposed by previous researchers, a defense scheme against the detector blinding attack by pulse illumination based on beam split detection is presented. Based on the countermeasures of detecting the working current of the device to judge whether there is a blinding attack, this scheme realizes the detection of bright light pulse with 100% probability before the detector is blinded, therefore, it can close the detection loophole of pulse illumination attack and improve the security of quantum key distribution systems.

The semi-quantum communication protocol allows participants with only limited quantum capabilities to carry out quantum communication. Compared with the full quantum communication protocol, it reduces the loss of quantum resources and saves the costs of quantum hardware. Based on a semi-quantum model, a novel semi-quantum private comparison protocol is proposed with the four-particle Greenberger-Horne-Zeilinger (GHZ) state as the quantum resource state. The protocol can compare the information of two classical users, Alice and Bob, with the help of a semi-honest third party without disclosing their secret information. Security analysis shows that this protocol can resist both internal and external attacks. Compared with the existing semi-quantum private comparison protocol, the classical user in the proposed protocol requires less quantum capability, only needs to perform Z-based measurement and reflect the received particles, and has high quantum bit efficiency. In addition, the proposed protocol is verified by simulation experiments on IBM quantum cloud platform.

Quantum secure direct communication does not need to prepare the quantum keys in advance, and secret information can be transmitted directly through quantums. In order to solve the problem of high cost of quantum communication equipment, a bidirectional three-party semi-quantum secure direct communication (SQSDC) scheme was proposed based on Greenberger-Horne-Zeilinger (GHZ) state and semi-quantum theory. The scheme can realize the secret communication between two classical parties and a quantum party. By adjusting the number of GHZ particles, the classical party can be extended to any number of parties according to the scheme, making the scheme particularly suitable for the communication between one superior unit and several subordinate units. The security analysis shows that, using the entanglement characteristics of GHZ state for eavesdropping detection can effectively resist the attack of eavesdroppers. In three-party communication, the communication efficiency of the scheme is up to 17.65%, showing a high communication efficiency.

Harrow-Hassidim-Lloyd (HHL) quantum algorithm has basically realized the function of solving linear equation Ax = b, and it is also the essential ingredient of many complex quantum algorithms. Although HHL quantum algorithm achieves exponential speedup over its classical counterpart, most of the current HHL quantum algorithms are abstract algorithm descriptions or their analyses. Especially, the HHL quantum circuits developed so far are small in scale and not general. By analyzing the basic units of HHL quantum algorithm, the key modules of HHL algorithm, including a unitary matrix decomposition module by general quantum gates, a quantum phase estimation module, a quantum full adder and multiplier module, and a conditional rotation module of quantum state, etc, were designed from top to down using general quantum gates, thus achieving a general quantum circuit for solving linear equations. Quantum simulations on the IBM qiskit quantum computation development platform show that the designed quantum circuits are suitable for solving more general linear equations and can be easily extended to medium or large-scale quantum circuits.

Multiple valued quantum logic has more advantages than binary quantum logic and is a promising research area in quantum computing technology. Adder circuits, as well as subtractor circuits, are the major components of various computational units in computers and other complex computational systems. A quaternary quantum reversible half-adder circuit is put forward, which consists of quaternary 1-qudit gates, 2-qudit Feynman gates and Muthukrishnan-Stroud gates, as well as a quaternary quantum reversible full adder and a quaternary quantum parallel adder circuit. The proposed designs are compared with the existing designs and the improvements on the performance of the proposed circuits are reported.

Using the spatial-spectral information of the altered license plates collected by hyperspectral lidar system, a twice-threshold method based on spectral feature is designed to recognize the altered license plates according to their retroreflection characteristics. Firstly, the characteristic wavelength of the spectra is selected, then the plate part and the altered material part are separated using the first threshold method according to the reflectance at the wavelength. Secondly, calculate the gradient value of the spectral reflectance curve at each point of the license plate part in the characteristic band, and the second threshold method is used to distinguish the alteration types, such as background to character alteration and character to background alteration. Finally, the correct license plate characters are reconstructed based on the type of the alteration, and the correct license plate image is reconstructed with the fusion of two-dimensional data and the corrected license plate characters, which is sent to the license plate recognition system. Experimental results show that this method can recognize altered license plates correctly regardless of different altered materials or different altered types.

Ultraviolet imagers have been widely used in electric power and other fields. In order to accurately locate and detect defects and faults such as electric discharge, a scientific and reliable test platform and the corresponding test methods with unified core performance have been established. Firstly, the sensitivity measurement method for traditional ultraviolet imager high temperature blackbody is critically improved, and a new measurement method based on the standard solar-blind ultraviolet light source and collimator is proposed, in which the light source, integrating sphere and control system are used to achieve optical imaging test, UV sensitivity test and out-of-band suppression test. Finally, a new test platform for the optical imaging performance, ultraviolet sensitivity and out-of-band suppression performance of the ultraviolet imager is developed based on the new method. It is shown that the test method and the developed test platform proposed in this work can better evaluate the real performance of the ultraviolet imager and meet the actual test requirements of the ultraviolet imager.

The transmission characteristics and transmission spectrum of a five-layer metal waveguide structure were studied under the excitation of a Gaussian beam. Firstly, the eigen equation of the waveguide were numerically solved to obtain the types and field distributions of the modes supported by the waveguide. Furthermore, assuming that the waveguide was excited by a Gaussian beam, the amplitude expressions of the different modes were calculated according to the angular spectrum distribution of the Gaussian beam and the mode coupling efficiency, and the transmission spectrum was obtained through the average power flow density at the outlet. It is found that when the refractive index of the central layer is increased by every 0.02, the minimum value of transmission spectrum shifts 35 nm each time, indicating that the waveguide can be used in a sensor for detecting central medium. The research will provide a theoretical reference for the application of waveguides in sensors and dielectric detectors.

The gas detection system composed of substrate-integrated hollow waveguide (iHWG) and Fourier transform infrared spectrometer (FTIR) has the advantages of small volume, fast response time, flexible optical design and good mechanical stability, which can be used for real-time online detection of pollution gases. The geometric parameters of iHWG, such as waveguide length, cross-section width and waveguide shape, can greatly affect the detection performance of FTIR-iHWG system. Based on the transmission theory of hollow waveguide, the influence of different geometric parameters is firstly analyzed on the transmission characteristics of iHWG. Then, four kinds of iHWG with different geometric parameters are designed using NO2 gas with a volume ratio of 100 × 10-6 as sample gas, and the correctness of the theoretical analysis is verified experimentally. The results show that under the same conditions, the larger the cross-section width of the waveguide, the higher the detection performance of the system. And for different shapes of iHWG, the linear iHWG system has better detection performance. The results of this work will provide useful reference for further optimization design of iHWG.