This paper presents the aerosol measurements in north suburb area of Nanjing and the analysis results. The aerosol in north suburb area of Nanjing is measured regularly by Raman-Rayleigh-Mie lidar system, and the results are analyzed. Variation of calculation result of aerosol extinction coefficient with boundary value is discussed in detail. The method for selecting more accuracy boundary value is suggested, and based on which, more accurate aerosol extinction coefficient is obtained. By comparing with other ground-based measurement results, it is indicated that aerosol Raman-Rayleigh-Mie lidar measurement results are comparable, and the method for boundary-value selection and aerosol extinction coefficient calculation is reliable.

Cirrus cloud has an important influence on the radiative balance in earth-atmosphere system, and cirrus cloud lidar ratio is helpful to understand the optical property of cirrus cloud. The retrieval methods of cirrus cloud effective lidar ratio are introduced, the features and application range of these methods are analyzed, and the reasons of selecting these methods are provided. System errors and random errors of these methods are estimated by case study. The results indicate that these retrieval methods are consistent and effective.

Stress produced in metallization of fiber Bragg grating (FBG) using electroless-electroplating method affects the sensing accuracy of FBG directly. Based on the mechanism of stresses, the changes of FBG′s transmission spectrum in metallization are studied for better sensing accuracy. Experiments show that electroless plated FBG exhibits broadened spectrum and reduced peak value. Theory and simulation analyses are conducted to study the stress in electroless plating. Results show that the thermal stress causes perturbation in FBG. Prolonging the cooling time is used to reduce the thermal stress. And during the electroless plating, the solution is mixed timely to make the stress uniform. It is shown that stress in electroless plating with the optimal condition affects the FBG little. The following electroplating experiments show that most stress is produced in the electroplating process. The changes of FBG′s spectrum are minimized by stabilizing higher electroplating temperature, mixing timely and using double electrodes. Finally, temperature sensor experiments for the metal coated FBG (MFBG) metalized under the optimized condition prove that the hysterisis error is reduced compared with the reported results.

In order to improve the coupling efficiency between fibers and optical devices, a new thermally expanded core fiber collimator is designed. It consists of thermally expanded core (TEC) fiber and gradient index (GRIN) lens. The relation between TEC fiber collimator and its optical characteristics is analyzed. The coupling insertion losses caused by three kinds of misalignments are calculated. The results show that the coupling characteristics of TEC fiber collimator is related to the GRIN lens parameters, the lateral and angular coupling tolerances have been greatly improved compared with single-mode fiber collimators and the loss of axial offset is higher than that of single-mode fiber collimators. We fabricate the TEC fiber collimator by using the TEC fiber with 15.4 μm mode-field radius and the GRIN lens with 0.295 mm-1 gradient constant. The coupling insertion losses measured are consistent well with the theoretical results. The TEC fiber collimator can be used for long working-distance optical coupling and rotary connection devices.

Methods related to the design of intensity modulation fiber-optic microphone are reviewed. A novel scheme to realize the reflective fiber-optic microphone by using single-mode fiber (SMF) fusing multimode fiber (MMF) is proposed and verified experimentally. The MMF with appropriate length and refractive index of parabolic distribution has the function of collimating lens, which is fused with a SMF. For this fiber-optic microphone, the structure is secure, the volume is miniature, and the cost is low. Also there is no intensity noise caused by the instability of higher order mode. By using single frequency sine wave signal source, the fiber-optic microphone is tested. The frequency of output sine wave voltage signal is the same as that of the drive source, and the change of amplitude is linear. The results show that the fiber-optic microphone can be used for voice communication.

The optimization parameters of high-power, high-efficiency erbium-doped superfluorescent fiber source are designed. Using commercial erbium-doped fiber, focusing on the double-pass backward architecture, the influences of the fiber length on output power and spectrum width of fiber source are simulated firstly. Then the corresponding experiments are done to validate the simulation results, thus to confirm the initial optimization fiber length ranges. The influences of reflectivity on fiber source performance are studied theoretically. The optimized reflectivity is calculated and the output spectra of fiber source under this reflectivity are simulated. The influences of pump power on mean wavelength are studied experimentally and the optimized pump power is confirmed, and thus the final optimized fiber length is further achieved. With 110 mW pump power and 13.74 m fiber length, we obtain the high power fiber source of 46.9 mW with the pump efficiency as high as 42.6% and the spectrum width of 34.54 nm.

A cladding-pumped single-mode ErYb-codoped fiber amplifier which is seeded by two lasers at 1535 nm and 1064 nm is designed to suppress the harmful Yb emission. An inband core-pumped fiber amplifier is constructed with the 1535 nm laser. The output power and spectrum of the amplifier are measured with different launched pump power. A 1.22 W maximum output power with 58.4% slope efficiency is achieved when the gain fiber is 5 m long, the seed laser power is 80 mW, and the 1535 nm pump power is 2.1 W. The output power and efficiency of a traditional amplifier whose pump source is 976 nm laser diode are also measured. The experimental results indicate that inband-pumped fiber amplifier can achieve higher efficiency than traditional fiber amplifiers.

The study process of the satellite-borne solar ultraviolet spectrometer is briefly introduced. The optical and mechanical structures of the ultraviolet spectrometer (SBUS) are introduced. SBUS is a compact, high-precision satellite-borne spectral radiometer. It can measure 160~400 nm solar ultraviolet-spectral irradiance under solar work modes. The calculation method and uncertainty factors of the measured ultraviolet spectral irradiance are analyzed. The measurement uncertainty analysis shows that the total uncertainty of the measured ultraviolet spectral irradiance is ±6.4% at 160~250 nm and ±5.2% at 250~400 nm. The data of solar ultraviolet spectral irradiance obtained by SBUS agree with the internationally published data with the deviation within ±5%.

S transform is a time-frequency analysis technique which combines the advantages of both short-time Fourier transform and wavelet transform. It maps a one-dimensional spatial signal into two-dimensional time-frequency domain and has a perfect time-frequency resolution. S transform has direct relation with Fourier transform and wavelet transform, and has the similar multiresolution ability of wavelet transform. It can be derived from Fourier transform coefficient and wavelet transform coefficient of a signal respectively, but the key technology that the implementation of S transform by wavelet analysis algorithm applied in three-dimensional optical measurements is rarely related at present. Focusing on the implementation of S transform by wavelet analysis algorithm, the application of S transform in three-dimensional optical measurement based on structured light projection is disussed, especially the selection of the frequency factor in S transform for obtaining good reconstruction. The reconstructed results of S transform profilometry based on fast Fourier transform and that based on wavelet transform are compared. The computer simulations and experiments verify our analysis.

The limitation of traditional threshold moment centroid algorithm for Hartmann wavefront sensor is analyzed. An improved algorithm is proposed, which the centroid detection window size is optimized and searched automatic with the gray integral principle, finally uses the intensity weighted centroiding algorithm to calculate. Simulation and analysis prove the feasibility, which is beneficial to improve the wavefront sensor centroid detecting accuracy.

A passively Q-switched Nd:YAG laser pumped by diode pulse is set up. The characteristics of the laser pulse intervals are analysed by combining numerical simulation and experimental method. Starting with the rate equation of passively Q-switching mode, the Q-switched pulse intervals are formulated in consideration of the feature of diode pulse pumping and the influence of surplus inverse population density. The in fluence of pumping current and pulse width, the reflectivity of output mirror and the initial transmission of Cr4+:YAG on pulse interval time is analysed enphatically. The result indicates that the numerical simulation of pulse interval time coincides with the experimental data.

When liquid crystal spatial light modulator is used for real-time adjustable beam shaping in inertial confinement fusion (ICF), Gamma curve with linear variation is of great significance. We present a new adjustment method for Gamma curve of liquid crystal spatial light modulator to vary linearly based on the existing hard sledding and time-consuming adjustment method. Discrete points for which gray values are used as abscissa and power values as ordinate are fitted to curve equation by Lagrange interpolation. Depending on the curve equation, the new gray values corresponding to the power values on the target Gamma curve are obtained with the gray value interval of 1 by Bolzano dichotomy. Then, replacing the original gray values with new ones makes the Gamma curve vary linearly. Using the new adjustment method for beam shaping in high-power laser amplifier facilities, super-Gaussian flat-top beam with a small near-field modulation and long-term stability is obtained.

Theoretical and experimental study is presented on near infrared band tuning and output characteristics of optical parametric oscillator based on periodically poled MgO:LiNbO3 (PPMgLN-OPO). The temperature tuning curve of PPMgLN is calculated. Through OPO experiments based on PPMgLN pumped by a 1.064 μm Nd:YVO4 laser, we realize tunable infrared laser output of 1.8~2.6 μm. We also compare the output characteristics of length of 2 cm and 3 cm PPMgLN crystals. When the pump power is 6.7 W, up to 3.2 W laser output in the 2 μm band is generated with a conversion efficiency of 47.8%.

The mixed powders of Co-based alloy (stellite-6) and vanadium carbide (VC) are deposited on SUS304 stainless steel using fiber laser and coaxial laser cladding head. The two methods with a constant chemical composition multi-layer cladding and a functionally gradient material multi-layer cladding are investigated comparatively. The results show that the microstructures of the clad layer with the mixed powder of stellite-6 and VC can be classified into hypoeutectic structure and hypereutectic structure according to the concentration of VC; the functionally gradient material multi-layer cladding is an effective method to decrease the crack sensitivity.

Nanostructures stripe deposition technique is a new method to develop nanostructures length standard transmission with the near resonance laser wave field manipultaion in neutral atoms. But all the information of nano-gratings deposited by laser standing wave field can not be given only through the one-dimensional or two-dimensional. The semi-classical model is used to simulate the three-dimensional trajectory and deposition distribution of the chromium atoms in the Gaussian laser standing wave field using the Runge-Kutta method from their motion equation in laser standing wave field. Then the three-dimensional deposition stripes are given, moreover, the effects of atomic beam divergence, chromatic aberration and spherical aberration on deposition structure are also analyzed. The study shows that results of three-dimensional simulation in Gaussian laser standing wave field of Cr can visually demonstrate the more detailed innate characters.

Spherical optical microcavities with different diameters (50~250 μm) are fabricated using polystyrene (PS), and they are coupled to tapered fibers. Absorption spectra of the spherical optical microcavities in wavelength range of 1570~1576 nm are measured. Experimental results show that whispering gallery mode (WGM)-based optical resonation occurs in the microcavities in this wavelength range. The wavelength interval between the adjacent resonating modes decreases with the increase of the PS sphere diameters. Quality factors of the PS spheres at the eigen frequencies are calculated according to the absorption spectra, and the results show that values of the quality factors are higher than 104.

The propagation of sinh-squared-Gaussian beams is investigated and the analytic solutions are obtained by means of an angular spectrum technique in uniaxially anisotropic crystals orthogonal to the optical axis. The propagation properties of the polarization components in crystals originating from sinh-squared-Gaussian beams are discussed with numerical method. The results show that the polarization properties cannot remain the same during propagation due to effects of anisotropic crystals. The field distribution of the beam polarized along the x-direction derives a y component. Along with the increase of the transmission distance, the polarization amplitude of the extraordinary ray along the x axis and the z axis are reduced, and the intensity also decreases. In addition, the propagation of the sinh-squared-Gaussian beams in anisotropic uniaxial crystals orthogonal to the optical axis can be influenced by the parameter β, and different β brings about different intensity distribution.

The one-dimensional photonic band gap of symmetrical structured consisting of the cycle unit of three single-negative materials in the form of (ABC)M(CBA)M are studied by the transfer matrix method. The results show that this kind of symmetrical structured one-dimensional photonic crystal has a special photonic band gap whose sensitivity to the angle of incidence is related to the nature of the light waves. TE wave high-frequency passband will move to the central frequency with the increase of the angle of incidence. The angle gap at the high-frequency band simultaneously enlarges with the increasing of the incident angle. But TM wave passband is not sensitive to the angle of incidence. When the ratio of the thicknesses of three media is unchanged, and the dielectric layers thickness is exponentially increased, high-frequency passband and low-frequency passband respectively shrank and narrowed, moving to the central frequency, and the low-frequency passband first disappears. When varying the ratio of the thicknesses of three media, keeping the A and C layer thickness unchanged and reducing the B layer thickness, high-frequency passband and low frequency passband respectively move to both sides and contract themselves at the same time. Maintaining the B layer thickness and increasing the A and C layer thickness, the high-frequency passband and the low-frequency passband are both shrunk, the low frequency passband first disappears. They all lead to the brodening of the band gap. We also found that the passband width of multiple heterostructures whose average permittivity and permeability are gradually narrowed with the increase of the lattice constant. This feature can be used to design omni-directional single-channel filters, and omni-directional zero-phase-shift filters.

Based on the propagation theory of paraxial approximation for optical beam, the analytical expression of the optical electric field is derived for the dipole vortex beam during propagation. The intensity distribution on the observation plane is obtained at the same time. It is shown that the obliquity of the dipole cores of the beam will change during propagation. While the topological charge is bigger, the center of spot on the observation plane tends to be a circular macula; while the off-center parameter is bigger, the center of the spot on the observation tends to be a rectangular bright spot. Further analysis on the extremum of the intensity reveals that if mw20>d2, there exists seven extreme points of light intensity on the observation plane; or else there exists five points.

Terahertz radar cross section (RCS) measurement is one of the most important techniques in terahertz applications. By using terahertz sources, the RCS of the targets and scale-models at terahertz band can be obtained, through which RCS of the full size targets at microwave band can also be calculated. Based on the definition of RCS and general requirements in the experiment, the main results of the terahertz RCS measurements abroad are provided. Three kinds of measuring facilities and targets and some typical measuring results are also emphasized. In the end, the characteristics in work frequency, size and miniaturization of targets and something else related when using terahertz time-domain spectrums system of femtosecond laser pumped crystal, inverse synthetic aperture radar system of CO2 laser pumped terhertz laser and coherent detection system with signal synthesizer are analyzed respectively, too. It helps to provide reference for the development of terahertz RCS measurement technology in our country.

Mid-infrared continuous-wave optical parametric oscillator (CW-OPO) is the focus in the field of nonlinear frequency conversion. It has important applications in optical communication, spectroscopy, remote sensing and infrared countermeasure. We analyzed the main features of the nonlinear crystal which is used to produce mid-infrared laser, and overviewed the experimental and theoretical researches of mid-infrared CW-OPO. We also proposed some of its future research directions. Currently, mid-infrared CW-OPO can achieve the output power from a hundred millwatts to ten watts in 3～ 5 μm with high stability, wide tunability. With the development of laser technology and periodically poled crystals with further improved performance, the next step is expected to achieve higher-power mid-infrared continuous-wave laser output in a larger tuning range.

With the rapid growth of internet business, optical networks will require better performance and higher capacity. Future optical networks are likely a hybrid of wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) by combining the advantages of both technologies. All-optical non-return-to-zero (NRZ) to return to zero (RZ) format conversion, which can enable data with different modulation format to transmit in different region of network freely, is one of the key interface techniques of constructing this hybrid network. The research progress of all-optical NRZ to RZ format conversion is introduced. And the operation principle, characteristics, performance are analyzed in detail. Also the advantages and disadvantages of these methods are listed. Finally, the future development is prospected.

As one of the research hot spots at home and abroad in the laser field nowadays, the applications of pulsed fiber lasers are becoming more and more extensive. Two typical configurations by which can obtain laser with nanosecond regime pulse duration are introduced and the key technologies of them are analyzed respectively based on the corresponding principles. Research progress at home and abroad in the field is summarized, then some problems to be resolved are put forward. At last the applications and develop prospect of pulsed fiber lasers are also presented.

In the visible and infrared regimes, optical nano-antennas are usually referred to metal nanoparticles and arrangement of the same, having distinct properties based on the localized surface plasmon resonance (LSPR). Optical antennas are generally characterized by their capabilities to strongly confine light, to enhance an optical response and even to modify emission directivity. On the basis of the principles of the surface plasmon, the charactistics of nano-antennas can be tuned by passive mode through changing design paramaters and active mode through an externally control. Optical nano-antennas have promising applications in the fields ranging from nano-optics, chemistry to biomedicine. This paper focuses on its most important functionalties and controlling modes, ended by a brief introduction in the applications in biomedicine.

Recently, whispering-gallery modes in an optical microcavity gradually become an important area of research owing to its high quality factor, small mode volumes and on-chip characteristics. The cavity without circular symmetry, which is called asymmetric microcavity, is a significant branch of microcavity research. The asymmetric microcavity breaks rounded symmetry, so the cavity has directional radiation. It couples with external environment efficiently. It may be used in integrated optics and free space optical interconnects. We review the research progress of asymmetric microcavity, including directional emission of high collimation, efficient free space excitation, ratchet microcavity, and three-dimensional asymmetric microcavity. The basic principles and the prospect development are also outlined.

Raman spectra of normal white blood cell (WBC) and diabetes mellitus (DM) WBC in vivo are studied by laser tweezers combined with multivariate statistic analysis method. Raman spectrum and multivariate statistic model is founded by the principal components analysis (PCA). The result of Raman spectrum suggests that DM WBC and normal WBC could be differentiated with PCA. Diagnostic specificity and sensitivity are nearly 98%. The protein vibration bands at 1302 cm-1 in DM WBC mouse in vivo show that the concentration of protein in DM WBC is higher than normal WBC. The Raman intensities at O-P-O of DNA and amide bands of DM cell are significantly higher than normal cell, which shows that the changes in the comformation of O-P-O and the backbone and hydrogen bonds of protein, as well as the second comformation of protein.

Raman spectrum and ultraviolet (UV) visible absorption spectrum of natural black saltwater pearls, dyed black pearls and radiated black pearls are analyzed and compared. It is found that natural black pearl, silver salt dyed pearl and radiated black pearl all have two peaks at 1080 and 699 cm-1 in raman spectrum. The fluorescence background of radiated black pearl is stronger. The peaks of dyed black pearl are correlated with the species of dyestuff. In UV-visible absorption spectrum, natural black pearl shows peaks at 284 and 357 nm, dyed black pearl has a peak at 380 nm, accounting for the displacement of 357 nm, while the peaks in ultraviolet region of silver salt dyed and radiated black pearl disappear. According to Raman and UV-visible spectral characteristics, non-destructive and effective identification of natural and color-treated black pearls is possible.

Total volatile basic nitrogen (TVB-N) content is an important index in evaluating the pork′s freshness. We attempt to determine TVB-N content in pork by multi-information fusion technique based on spectroscopy and imaging. In experiment, pork samples with different freshness are studied, and the near-infrared spectra and images are collected simultaneously. Principal component analysis (PCA) is implemented on these feature variables from image and spectral information, and a prediction model is developed by the back-propagation artificial neural network (BP-ANN). Experimental results show that the model based on multi-information fusion is superior to the model based on a single technique, the root mean square error of cross-validation in the model is 1.2975, and the correlation coefficients is 0.957 when the model is tested by independent samples in the prediction set. The overall results show that it is feasible to measure TVB-N content in pork by multi-information fusion based on spectra and imaging, and the performance from the model based on multi-infusion fusion is better than that from the model based on a single technique.