Exo-atmospheric targets are especially difficult to distinguish using currently available techniques, because all target parts follow the same spatial trajectory. The feasibility of distinguishing multiple type components of exo-atmospheric targets is demonstrated by applying the probabilistic neural network. Differences in thermal behavior and time-varying signals of space-objects are analyzed during the selection of features used as inputs of the neural network. A novel multi-colorimetric technology is introduced to measure precisely the temporal evolutional characteristics of temperature and emissivity-area products. To test the effectiveness of the recognition algorithm, the results obtained from a set of synthetic multispectral data set are presented and discussed. These results indicate that the discrimination algorithm can obtain a remarkable success rate.

The intensifying process of polarization effect at room temperature in a pixellated Cadmium zinc telluride (CdZnTe) monolithic detector is studied. The process is attributed to the increase in build up space charges in the CdZnTe crystal, which causes an expansion of the space charge region under the irradiated area. The simulations of electric potential distributions indicate that the distorted electric potential due to the high X-ray flux is significantly changed and even deteriorated due to increasing space charges within the irradiated volume. An agreement between the space charge distribution and electric potential is discussed.

A new optical label switching system with coherently detected implicit spectral amplitude code (SAC) labels is proposed in this letter. The implicit SAC labels are recognized using a frequency-swept local light source oscillator. Intensity modulation payloads of 625 Mb/s and 1.25 Gb/s are considered. Label and payload bit error rate (BER) performances are assessed and compared by simulations. The results reveal that, at a BER value of 10^{-9}, -32.4-dBm label received power can be obtained. In addition, 8.3-dB optical signal-to-noise ratio (OSNR) is obtained when carrying a payload of 625 Mb/s. The label BER value hardly reaches 10^{-9} if the payload bit rate is at 1.25 Gb/s; however, a high payload bit rate only has little influence on received payload quality at a BER value of 10^{-9}. Finally, a payload of 1.25 Gb/s could obtain -28.2 dBm received power and 9.5-dB OSNR.

Signal degradation due to physical impairments may result in unacceptable bit-error rates of received signals at the destination. Based on earlier work, we study the impairment-aware quality of service (QoS) provisioning problem in dual-header optical burst switching (OBS) networks that employ two control packets for each data burst. At an OBS node, the proposed algorithm schedule bursts for transmission by searching for available resources using admission control and preemption. The algorithm also verifies signal quality. Simulation results show that this algorithm is effective in providing QoS support in OBS networks while considering physical impairment effects.

Using conventional coupled-mode theory, a set of coupled-mode equations are formulated for single-helix chiral fiber long-period gratings. A helical-core fiber is analyzed as an example. The analysis is simple in mathematical form and intuitive in physical concept. Based on the analysis, the polarization independence of mode coupling in special fiber gratings is revealed. The transmission characteristics of helical-core fibers are also simulated and discussed.

The combination of fast polarization scrambler (FPS) and forward error correction (FEC) is one of the methods to mitigate the polarization mode dispersion (PMD) in high-speed optical fiber communication systems. The effect of the different distribution patterns of FPS on PMD mitigation with FEC is investigated. A comparison of the bit error rates (BERs) between two cases where the distributed FPS is absent and present along the fiber is carried out by simulation. A novel representation called the "ring chart" to assess the performance of different distribution patterns intuitively is proposed. The results show that the distribution pattern is an impact factor for this PMD mitigation scheme.

We demonstrate the rotating properties of Bragg reflections and spatial lattice solitons in rotating photonic lattices by analyzing the linear and nonlinear propagations of light. It reveals that the Bragg reflection of the light waves rotates synchronously with the lattices, leading to the rotation of the Bloch waves during propagations. In the presence of nonlinearity, rotating lattice solitons from different transmission bands can propagate in a relatively stable manner. However, reduced-symmetry solitons at point X2 cannot easily rotate synchronously with the lattice, owing to Coriolis forces. Moreover, additional angular momenta are added to the off-axis propagating solitons.

A novel hybrid fitting energy-based active contour model in the level set framework is proposed. The method fuses the region and boundary information of the target to achieve accurate and robust detection performance. A special extra term that penalizes the deviation of the level set function from a signed distance function is also included in our method. This term allows the time-consuming redistancing operation to be removed completely. Moreover, a fast unconditionally stable numerical scheme is introduced to solve the problem. Experimental results on real infrared images show that our method can improve target detection performance efficiently in terms of the number of iterations and the wasted central processing unit (CPU) time.

The use of a compact disk (CD) pickup head as a displacement measurement system is described. The components contained in a pickup head are explained and how they are combined to obtain the functionality of a pickup head. The application of measuring a knife edge profile is introduced. The results reveal some insuffiencies with the current system. The cutting edge’s radius of curvature can be estimated.

The measurement of boreholes with diameters smaller than 500 μm is a demanding task that cannot be performed using state-of-the-art production metrology. In this letter, a miniaturized fiber probe with a diameter of 80 \mu m is presented. A probe is used for low-coherence interferometry to conduct highly precise measurements of form deviations of small boreholes. Measurements conducted in nozzles are also presented. The results prove the potential of the fiber-optical sensor for quality inspection of high-precision parts, such as injection nozzles, for common-rail diesel engines.

Applying laser-speckle techniques in material sciences as well as in methods to characterize surface conditions of specimen has become the method of choice, especially if a non-contacting principle is sought. This is almost always the case for specimen that are small in at least one dimension as for example in the material testing of foils, fibres, or micromaterials and certainly also if elevated test-temperatures are preventing standard gauges. This letter discusses in some detail sources of error that are quite often overlooked or not even considered as signiˉcant at all, but still carry the potential to introduce uncertainties well above the system design specifications.

A high-powered millijoule pulse energy Tm3+-doped fiber amplifier seeded with a Q-switched operation of Tm (4 at.-%), Ho (0.4 at.-%):YVO4 laser is reported. The output characteristics of the amplified laser are studied at the coupled powers of 0.266, 1.24, and 2.65 W. Maximum output power up to 15.7 W is at 10-kHz repetition rate. Nonlinear effects are not observed from the emitting spectrum and the full-width at half-maximum (FWHM) of the pulse duration is reduced from 40.1 to 25.9 ns at 1.57-mJ pulse energy. The beam quality factor M2x=1.9\pm 0.03, M2y=2.1\pm 0.02 at the output power of 14.5 W is measured using the traveling knife-edge method.

The microstructure characteristics of laser forming repaired (LFR) Ti60 (Ti-5.6Al-4.8Sn-2Zr-1Mo-0.35Si-0.3Nb) as-deposited and annealed samples are analyzed. The microstructure of as-deposited repaired zone (RZ) consists of epitaxial columnar prior \beta grains, in which fine woven \alpha laths and \beta-phase between \alpha laths exist. The heat-affected zone (HAZ) experiences a continuous microstructural transition from duplex microstructure of the base metal zone (BMZ) to the microstructure of RZ. The presence of silicide precipitates is observed in both RZ and BMZ in an annealed sample by transmission electron microscopy. They are identified as (Ti, Zr)6Si3 distributed mainly at the \alpha/\beta interface with the size of 100-300 nm. The fine \alpha2 precipitates are detected in BMZ by electron diffraction; there was no \alpha2 detected in RZ.

By aiming the pump wavelength of the laser diode to the absorption peak at 811 nm of the (Nd0:005Lu0:4975Y0:4975)2SiO5 (Nd:LYSO) crystal, an efficient dual-wavelength operation at 1,075 and 1,079 nm is obtained. The maximum output power is 702 mW when the incident pump power is 2.53 W, corresponding to an optical conversion efficiency of 27.7% and a slope efficiency of 37.0%.

In this letter, a thin slab of glass is used as Fabry–Perot etalon inside a cavity of a continuous wave (CW) Nd:YAG laser to change the behavior of its output longitudinal modes. The slab etalon is used as tuning element when it turns around the laser cavity axis. Two simultaneous longitudinal modes with a relatively wide tuning range from 5.83 MHz to 0.02 THz are obtained when the Nd:YAG laser is operated at moderate output power of about 120 mW. The mode structure of this configuration is modeled and simulated. Computer-generated diagrams are also presented schematically and compared with the experimental results.

An ultrabroadband supercontinuum (SC) is demonstrated in a pure silica photonic crystal fiber (PCF) pumped by quasi-continuous wave nanosecond-long pulses at 1,064 nm. The generated SC spectra extending from 450 to at least 2,400 nm have the salient feature of a short wavelength regime below the pump wavelength, which is much higher in intensity than the long-wavelength over the pump wavelength. The influence of pump power and repetition rates on SC generation (SCG) is explored. Results suggest that this pump source has both the advantages of short-pulse and continuous-wave pumps for SCG.

An efficient high-power diode-pumped femtosecond Yb:KGW laser is repored. Through optimization of energy density by semiconductor saturable absorber mirror, output power achieved 2.4 W with pulse duration of 350 fs and repetition rate of 53 MHz at a pump power of 12.5 W, corresponding to an optical-to-optical efficiency of 19.2%. We believe that it is the highest optical-to-optical efficiency for single-diode-pumped bulk Yb:KGW femtosecond lasers to date.

Bi-doped SiO2–Al2O3–GeO2 fiber preforms are prepared by modified chemical vapor deposition (MCVD) and solution doping process. The characteristic spectra of the preforms and fibers are experimentally investigated, and a distinct difference in emission between the two is observed. Under 808-nm excitation, an ultra-broad near-infrared (NIR) emission with full-width at half-maximum (FWHM) of 495 nm is observed in the Bi-doped fiber. This observation, to our knowledge, is the first in this field. The NIR emission consists of two bands, which may be ascribed to the Bi0 and Bi+ species, respectively. This Bi-doped fiber is promising for broadband optical amplification and widely tunable laser.

In this letter, Eu2+-activated MO-B2O3 (M=Ca, Sr, and Ba) glasses are prepared in reductive atmosphere and their long lasting phosphorescence properties are studied. The intensity of the phosphorescence for the glasses is Sr>Ca>Ba. The light-induced electron paramagnetic resonance signal is observed after the irradiation of an ultraviolet lamp, which is due to the electron trapped by oxygen vacancy. The energy depth of the glasses is calculated using Hoogenstraaten's method.

The omni-directional reflection characteristics of one-dimensional photonic crystals composed of Ta2O5/MgF2 multi-quantum well (MQW) are studied using the transfer matrix method. An omni-directional reflector consisting of three and four Ta2O5/MgF2 MQWs is investigated. Results show that the photonic band gap of the photonic crystal composed of three and four Ta2O5/MgF2 MQWs, which are within the wavelength ranges of 402–712 and 412–1,023 nm, respectively, could cover the entire visible region. The relationship among the width of the band gap, its location, reflectivity rate, and incident angle of the incident light is analyzed. The optimal structural parameters of the MQW of the omni-directional reflector in the visible region are also calculated. The calculations provide a guide for the design of omni-directional reflection devices in the visible region.

Using 300-fs 1039-nm Yb-doped fiber laser, we experimentally demonstrate blue light generation in a high-\Delta and high nonlinear photonic crystal fiber (PCF). The zero dispersion wavelength of PCF is 793 nm, detuning 245.8 nm from the pump wavelength. PCF allows a frequency conversion exceeding the octave of pump wavelength. The visible component of the measured output spectrum occurs in the fundamental mode and spans from 391.3 to 492.3 nm. The peak wavelength of 441.8 nm has a frequency detuning of 390 THz from the pump wavelength of 1039 nm.

Polarization dependence of the enhancement and suppression of four-wave mixing (FWM) in a multi-Zeeman level atomic system is investigated both theoretically and experimentally. A dressing field applied to the adjacent transition can cause energy level splitting. Therefore, it can control the enhancement and suppression of the FWM processes in the system due to the effect of electromagnetically induced transparency. The results show that the pumping beams with different polarizations select the transitions between different Zeeman levels that, in turn, affect the enhancement and suppression efficiencies of FWM.

The Bell-nonlocality of two initially entangled macroscopic fields in the double Jaynes-Cummings model is investigated. Moreover, the process by which detuning between the atomic transition frequency and the field frequency affects the evolution of the Bell-nonlocality of two macroscopic fields is studied. The effect of the disparity between the two coupling strengths is discussed.

Dielectric microspheres can confine light in a three-dimensional (3D) region called photonic nanojet is shown when they are illuminated by different polarized beams. The influence of incident light polarization on photonic nanojet using the finite-difference time-domain (FDTD) method is demostrated. The axial field intensity profiles of photonic nanojets for both the linear and circular polarization incident beams are very similar. Azimuthal polarization incident beam induces a doughnut beam along the optical axis, while the radial polarization incident beam permits one to reach an effective volume as small as 0.7(\lambda/n)3.

We report a new structure for broadband antireflection coating by dip-coating technique, which has minimal cost and is compatible with large-scale manufacturing. The coatings are prepared by depositing SiO2 sol-gel film on a glass substrate, subsequently depositing SiO2 single-layer particle coating through electrostatic attraction, and depositing a final very thin SiO2 sol-gel film to improve the mechanical strength of the whole coating structure. The refractive index of the structure changes gradually from the top to the substrate. The transmittance of a glass substrate has been experimentally found to be improved in the spectral range of 400-1,400 nm and in the incidence angle range from 0o to at least 45o. The mechanical strength is immensely improved because of the additional thin SiO2 sol-gel layer. The surface texture can be applied to the substrates of different materials and shapes as an add-on coating.

Conventional printer characterisation models are generally based on the assumption that the densities of primary colours are additive. However, additivity failure frequently occurs in practice. We propose a novel grey component replacement (GCR) method based on the spectral density sub-additivity equations in this letter for spectral characterisation of a 4-ink colour printer. The method effectively correct the error caused by additivity failure. Real high-quality hardcopy samples are produced as evidence of the feasibility of the proposed method and to evaluate the model performance. Finally, the GCR model for characterising colour printer with high spectral and colorimetric prediction accuracy is established.