With the rapid development of semiconductor growth technology and packaging technology, the performance of high power and high brightness semiconductor lasers has been continuously improved, which plays an important role in industrial processing, biomedical, national defense, as well as pumping source of fiber lasers and solid-state lasers. In recent years, the power and beam quality of side-emitting semiconductors have been improved, which makes the output power coupled to optical fibers continuously improve. The output of fiber coupled single emitter has been gradually improved from milliwatt to tens of watts, even hundreds of watts through polarization, spectrum or space combining technology. In the field of stacked array or multi-linear array fiber coupled laser, the output has also been improved from tens of watts level to tens of kilowatts level. Starting from three kinds of semiconductor lasers including single emitter, linear array and stacked array, the development status and technology of semiconductor lasers are investigated and analyzed, and the various shaping, bunching and coupling technology of fiber-coupled semiconductor lasers are also summarized and prospected.

Off-axis integral cavity output spectroscopy (OA-ICOS) has the advantages of high sensitivity and strong environmental robustness. After the re-injection method is introduced, the signal power of OA-ICOS is effectively improved. It alleviates the problem that the detection sensitivity is highly dependent on the power of light source, and makes it possible to use low-power laser and high-reflectance cavity mirror to build the high sensitivity OA-ICOS. However, due to the special optical structure of the method, the detection signals tend to be doped with relatively strong interference noise. For interference problem, a re-injection OA-ICOS device is designed and built to measure the actual atmosphere CO2. The noise introduced by the re-injection structure is studied, and disturbance method is proposed to decrease the noise. Results show that the disturbance method reduces the amplitude of noise signal from the original 467.3 mV to 61.2 mV, which is 7.63 times lower. The method has the advantages of lower cost and easier implementation.

The traditional spectral-based remote sensing image change detection methods usually adopt spectral mean, brightness, standard deviation and other features for difference calculation. However, these features have a certain degree of correlation, resulting in a lot of false detection of change detection results, and the selection of threshold has a greater impact on the change detection results. The traditional detection methods using spectral features are mostly based on pixels, and the detection results have salt and pepper phenomenon. In order to solve these problems, an object-oriented spectral component substitution change detection method is proposed, which mainly uses the single-band spectrum of two-phase images for combination substitution, so as to highlight the change information. The change information is extracted by classification method. The experimental results show that the change detection accuracy of proposed method can reach 86%. The proposed method is simple and effective, and it can effectively assist land use change monitoring, geographical and national conditions cover change monitoring and other production projects.

The absorption spectrum of natural abundan ce water vapor at 1.51 μm has been studied at room temperature by using a high-resolution tunable diode laser absorption spectrometer (TDLAS) combined with a long-path White absorption cell. A total of 57 absorption lines are investigated within the laser spectral range (6608～6624.3 cm-1). The line positions, line intensities and self-broadening coefficients of these lines are obtained by using a nonlinear least-squares fitting method, and then compared with the available values reported in the HITRAN 2016 database. Results show that the experimental data of present work is in good agreement with those from HITRAN 2016 database, which indicates that the spectral measurement system is suitable for study on the spectra of water vapor.

Aiming at the problems of complex structure, large volume and difficult integration of multi-channel aerosol detection system for photoacoustic spectroscopy, a design of integrated modulation signal generation system capable of generating multi-channel parameter adjustable pulse-width modulation(PWM) wave is proposed. The system is based on STM32 processing and LabVIEW program. It realizes synchronous modulation of multi-channel photoacoustic spectroscopy by generating PWM signals with multi-channel frequency and adjustable amplitude. The specific indicators are the following. The amplitude, frequency and sweep frequency are continuously adjustable from 0 to 9 V, from 1 MHz to 72 MHz, from 550 Hz to 6000 Hz, respectively. Experiments show that the multi-channel photoacoustic spectroscopy system with tunable PWM wave integrated system is reliable, stable and easy to operate. The signal is consistent with that of commercial signal generator modulation, which proves the feasibility and reliability of the designed multi-channel modulator. The proposed design can provide reference for the integrated design of photoacoustic spectroscopy or other spectroscopy detection systems.

Due to large flux, wide spectral range, high resolution and many other advantages, Fourier transform infrared spectroscopy has been widely used in the field of atmospheric environment monitoring. Based on the weak infrared interference optical signal characteristic of Fourier transform infrared spectrometer and the tellurium cadmium mercury photoconductive type infrared detector, the characteristics of the interference optical signal of the Fourier transform spectrometer based on the Michelson interference method are analyzed. A kind of weak signal detection circuit taking narrowband filtering method as the core is designed, and the equivalent noise model is established to analyze the noise performance of the circuit. The circuit is simulated by Tina software. Results show that the circuit has constant gain and group delay in the pass band, and the weak interference signal can be amplified without distortion.The designed circuit is applied to the Fourier transform spectrometer, and the atmospheric mid-infrared band spectrum ranging from 400～7000 cm-1 is obtained at room temperature, almost covering the common absorption peak of atmospheric pollutants in the mid-infrared band, which can achieve the identification and measurement of different pollutants.

It is always difficult to extract the single pure spectral data from the mixed gas spectrum with severe overlap. In order to obtain the ideal unmixing precision, an improved non-negative matrix factorization algorithm is proposed, in which the correlation constraint and smoothness constraint of the spectrum is introduced, and the iterative step size of the optimized gradient descent method is given to avoid the effects of algorithm convergence to local instability. The improved algorithm combines the decomposition error of the matrix and influence of the mixed spectral characteristics. The experimental data show that the demixing results obtained by the improved non-negative matrix factor can accurately resolve the characteristic peak shape of each source spectrum, and there is almost no mixed superimposed influence between the demixing results, which can satisfy the subsequent spectral recognition work.

In order to realize polarization imaging of the target penetrating glass and film, the polarized imaging model of penetrating glass and film is established according to the physical transmission process of light. The transmission coefficient of glass and film is estimated combining with the characteristics of optical modulation transfer function. An information reconstruction method of image of penetrating glass and film is put forward by using the orthogonal polarization components of the target light and ambient light. The curve fitting method, polarization filtering and frequency domain iterative algorithms are used to estimate the parameters in the reconstruction algorithm, and finally the image of penetrating glass and film is reconstructed. The experiments are carried out in indoor simulation conditions and outdoor environment. Results show that the method can effectively reconstruct the target information of people and scenes in the image of penetrating the glass and film.

Fault diagnosis systems have become an important aid to ensure the safe operation of industrial systems and equipments. In the early stages of the fault, the diagnosis system can quickly provide early warning information and reference for the development of the fault mitigation plan. For this purpose, a fault diagnosis method based on optical gray image recognition is proposed. The method constructs the running state image of the system according to the real-time monitoring data, intercepts the gray image by CCD recording, and extracts the gray image from different resolution systems. The grayscale image features of the system are extracted from the approximate histogram. Based on the Euclidean distance between these features and the standard features, the current state is divided into the standard feature classes with the smallest distance. The experimental results show that the method can detect the fault type quickly and correctly, and can provide effective support information for the system related design and maintenance personnel.

It is a remarkable advantage of organic-inorganic hybrid perovskite that their bandgap can be tuned by adjusting the stoichiometric ratio of halides, which is critical to their applications in tandem solar cells, wavelength-tunable light emitting diodes (LEDs) and laser. However, illumination or applied bias will cause the phase separation of mixed-halide perovskite, resulting in the formation of iodide-rich domains, the reduction of photovoltaic devices open-circuit voltage, and the emission wavelength of luminous LED being pinned to the infrared region. The phase separation is suppressed by covering self-assembled long-chain organic ammonium capping layers on nanometer-sized grain surfaces, and the LED with stable emission wavelength is obtained with external quantum efficiency being improved to 2%.

The low phase-noise and high frequency-stability 10 MHz hydrogen clock signal (HCS) is the indispensable microwave frequency reference for physics experiments of precision measurement. After transmitted over a certain distance, the phase noise and short-term stability of the HCS will be downgraded due to the disturbance of the external electromagnetic noise and vibration. A scheme to filter the terminal noise of the HCS after transmission is introduced, which reduces the phase noise and improves the short-term stability of the HCS. The scheme is based on phase-locking of an oven-controlled crystal oscillator (OCXO) to the HCS, the phase noise and frequency stability of the reference signal at shorter than 1 s is defined by the OCXO, while the long-term stability follows the HCS. After the filtering scheme, the power of the HCS is amplified from -4.4 dBm to 5 dBm, the terminal phase noise background of the HCS is reduced about 10 dB, and all disturbance higher than 1 Hz are eliminated. The system can dramatically purify the HCS without changing the laboratory hydrogen clock and the HCS transmitting network, and then the accuracy of precision measurement experiment is improved.

A controlled quantum secure direct communication scheme based on GHZ-like state is proposed. In the scheme, combining with the quantum CNOT operation, three participants of the communication use the entangled particles in their respective hands which satisfy the nature of the classical XOR relationship to encrypt, control and decrypt the quantum state carrying classical information. Meanwhile, decoying photons is used to prevent eavesdropping and ensure the security of communications. Security analysis shows that the proposed scheme can effectively detect the eavesdropping behavior of internal and external eavesdroppers. At the same time, the message particles transmitted in the communication process are not entangled particles distributed, so the entangled resources in this scheme can be reused.

A remote state preparation protocol for a known four-quantum entangled state is proposed, in which there are two possible receivers, and the sender can choose one of the two possible receivers to prepare an intended quantum state at the chosen receiver. The sender first introduces two auxiliary quantum particles and performs two controlled non-gate operations. Then two projection measurements on two-particle systems are carried out, where the measurement bases are chosen by using the information of the known states. At last the sender exercises her option which is exclusively her own prerogative. According to sixteen different measurement results of the sender, the protocol consists of sixteen parts. The intrinsic efficiency of the scheme is given, and its comparative advantages are also pointed out by comparing with the existing corresponding schemes.

Quantum key distribution (QKD) allows two remote parties to generate a theoretically secure key. However, the imperfections of the light source and measuring device often exist in practice, which causes different attacks on the quantum key distribution system. To eliminate these attacks, the researchers proposed a twin field QKD protocol. The protocol encodes the key information in the phase of the photons so that the photons are easily transmitted and maintained, which not only extends the transmission distance, but also solves the safety problem of the measuring device. Inspired by this, a new B92 protocol based on phase encoding is proposed. Compared with the original B92 protocol, the new protocol not only eliminates the attack of the detector, but also imporves the key rate. There is no need for a base step in the post-processing process in this new protocol, and only two non-orthogonal quantum states are used by both communicating parties, and moreover, it is easy to implement in practice.

The structure parameters, semiconductor characteristics and process morphology of silicon micro-ring resonators have important effects on the output repetition frequency of correlated photon-pair sources. The nonlinear loss of crystalline silicon is included in the simulation calculation of the output repetition frequency, and the spontaneous four-wave mixing effect model of all-pass silicon micro-ring resonators is deduced. Effects of the parameters such as the quality factor of all-pass silicon micro-ring resonators, radius of micro-ring resonators and free carrier life of crystalline silicon on output repetition frequency are investigated by using the model. Results show that when the external quality factor is 5×104, the pumping power reaches 15 mW and continues to increase, the output repetition frequency of the correlated photon-pairs decreases. Ideally, the smaller the radius of the micro-ring resonators is, the higher the output repetition frequency will be. For the silicon micro-ring resonators correlated photon-pair sources, the preferred solution to increase the output repetition frequency is to reduce the free carrier lifetime.

In order to extend harmonic cutoff energy and enhance harmonic radiation intensity, a method using the combined field of chirped laser and ultraviolet laser to drive He atoms to regulate the harmonic radiation process is proposed. Results show that driven by the single-color field, the harmonic cutoff energy is extended with the introduction of negative chirp. Moreover, as the laser pulse width increases, the harmonic cut-off energy further extends. When the second laser field is introduced, the harmonic cutoff energy extends slightly. At the same time, the harmonic radiation intensity is enhanced by three orders of magnitude. When the third beam ultraviolet laser field is introduced, the harmonic radiation intensity is enhanced by two orders of magnitude compared with that of the two-color field. As the intensity of ultraviolet laser is increased, the intensity of harmonic radiation is further enhanced. Finally, an isolated attosecond pulse with a pulse width of 38 as can be obtained by superposing the harmonics of the spectral continuum region.

Based on the theory of non-Kolmogorov turbulence spectrum, the mathematics and physics model of laser propagation in non-Kolmogorov spectrum turbulence atmosphere is established, and numerical simulation is carried out based on the model. Results show that the turbulence spectral index has important effects on the laser propagation characteristics and its phase compensation. Under the condition of the same generalized atmospheric refractive index structure constant, the laser beam quality of far-field is better when turbulence spectral index is close to both ends of the interval (3,4). When turbulence spectral index is nearly to 4, the effect of adaptive optics compensation is better. Under the condition of the same generalized atmospheric coherence length, the peak Strehl ratio increases with the increase of turbulence spectral index. The laser propagation characteristics under normalization power spectrum are discussed, and the propagation mechanism of laser in non-Kolmogorov turbulence atmosphere is preliminary revealed.

There is some axial extension in the applying scale of linearly chirped fiber Bragg grating(LCFBG) with transverse strain, which should be considered when the length of the applying scale is the same order of magnitude as the diameter of fiber. Based on the analysis of spatial elasticity, phase shift in the modulated refractive index distribution of LCFBG resulting from the axial extension is obtained. And the transmission spectrum peak created in grating spectrum is related to the value and position of phase shift. Furthermore, transverse strain can lead to birefringence. Considering all the factors aforementioned, the theoretical sensing model of transverse strain in small applying scale that can be treated as a point is introduced, in which the Stokes parameter characteristics of LCFBG are very important and useful. Simulation and analysis results show that the transmission coefficient grows exponentially with transverse strain but the peak value of transmission Stokes parameter spectrum is linearly dependent on the value of transverse strain applying in LCFBG. There is a one-to-one correspondence between the peak wavelength of transmission Stokes-s1 parameter spectrum and the applying position of transverse strain. And the peak wavelength of transmission Stokes-s1 parameter spectrum grows linearly with the value of transverse strain. So the position and value of transverse strain in small applying scale can be converted through the analysis method of measuring the transmission Stokes-s1 parameter spectrum of LCFBG.