Cold ⁸⁷Rb atom's loading in an integrating sphere with diffuse light is analyzed theoretically and experimentally. The experimental results show that diffuse light cooling has the greatest efficiency to cool the most atoms when the red detuning between the frequencies of cooling light and atom transition is about 3.3\Gamma (\Gamma is the natural linewidth, 6.065 MHz). Theoretical analysis using rate equation and numerical calculations on the cold atom number and loading time agree with the experimental results. This integrating sphere cooling would be a novel method for cooling atoms and lead to a new and robust cold atom source for atomic clock.

A photon sieve can be composed of a large number of circular pinholes. Each circular pinhole has a contribution to the focusing. For the case of point-to-point imaging, the focusing contribution of an individual circular pinhole can be analytically given. We investigate the dependence of the focusing contribution on the order m of local ring of underlying traditional Fresnel zone plate. In particular, we find that the focusing contribution is simply inversely proportional to the order m. We also present an intuitive explanation. These results are helpful for better understanding of the focusing property of photon sieves.

A novel band-rejection filter based on a Bragg fiber with a defect layer is proposed. A defect layer is introduced in the periodic high/low index layers in the cladding of the Bragg fiber, which results in large confinement loss for some resonant wavelengths inside the band gap range of the Bragg fiber. A segment of the Bragg fiber with a defect layer can be used as a band-rejection filter, whose characteristics are mainly determined by the structure of the Bragg fiber. The simulation results show that the bandwidth of such a band-rejection filter is dependent on the number of the periodic high/low index layers in both sides of the defect layer in the cladding of the Bragg fiber.

The dispersion of Yb-doped fiber is measured by a spectral interferometric technique. The experimental verification is achieved by comparing the measured data with published data of the Nufern 1060xp fiber and the measurement relative error is 1.36%. The parameters of the experimental system, such as minimum required source bandwidth and minimum fiber length, are introduced and analyzed in the measurement. The minimum required source bandwidth predicted through theoretical calculation at the center wavelength of 1070 nm is 19.3 nm, which perfectly agrees with the experimental value.

A sensitive polymer diaphragm based fiber Fabry-Perot (F-P) sensor for aeroacoustic wave measurement is presented. A novel polymer material poly (phthalazinone ether sulfone ketone) (PPESK) diaphragm is used as the acoustic sensing element. The effective dimensions of the diaphragm are 4 mm in diameter and 6 \mu m in thickness. Owing to the good mechanical and optical features of the diaphragm and application of the interferometric/intensity demodulation, a system sensitivity of 31 mV/Pa is achieved in the frequency range of 0.1-12.7 kHz, and a signal-to-noise ratio (SNR) of 29 dB at 1 kHz is obtained. The linear response of the sensor is from 0.35 to 2.82 Pa, corresponding to 85-103 dB sound pressure level (SPL) (re: 20\mu Pa). The sensor has the potential to be used as a universal and low-cost optical microphone.

Two novel dynamical quality of transmission (QoT) optimization schemes with explicit optimization targets and accurate end-to-end QoT estimation are proposed for reconfigurable transparent wavelength-division multiplexing (WDM) networks. Numerical simulations show that the scheme of quality (Q) best has the best Q factor improvement with large attenuation adjustment. The scheme of Q allowable can achieve minimized number of tuning sites and attenuation adjustment and also improve the Q factor of light path to the required value. In addition, the idea of dynamic QoT optimization and global impairment control has been experimentally demonstrated on a simple mesh network by the cooperation of a control plane and tunable devices.

Experimental implementations of continuous optical time domain Fourier transformation based on time lenses and optical orthogonal frequency-division multiplexing (OFDM) system are carried out. Such a system is verified through 100-km transmission of 10-Gb/s non-return-to-zero (NRZ) intensity-modulated direct-detection (IM-DD) without any dispersion compensation. The system's bit error rate (BER) and power penalty are 10^-12 and 4 dBm, respectively.

A new method for simultaneously determining the size and refractive index of epithelial cell nuclei is presented. The function of the modified elastic light scattering spectrum is regarded as a function of wave number factor, Q=2\lambda^-1 sin(\theta/2). The modified spectrum has a constant oscillation period with its frequency proportional to the average diameter of cell nuclei. To the same average diameter, the different relative refractive indexes of epithelial cell nuclei only induce the horizontal shift of the spectra. Both the oscillation frequency and the horizontal shift are quantified by the fast Fourier transform on the modified spectra. The average diameter can be figured out through the peak frequency divided by the value of the refractive index of the surrounding medium. The phase angle of the peak frequency has an approximate linear relationship with the relative refractive index of epithelial cell nuclei.

A digital still camera image processing system on a chip, different from the video camera system, is presented for mobile phone to reduce the power consumption and size. A new color interpolation algorithm is proposed to enhance the image quality. The system can also process fixed patten noise (FPN) reduction, color correction, gamma correction, RGB/YUV space transfer, etc. The chip is controlled by sensor registers by inter-integrated circuit (I²C) interface. The voltage for both the front-end analog and the pad circuits is 2.8 V, and the volatge for the image signal processing is 1.8 V. The chip running under the external 13.5-MHz clock has a video data rate of 30 frames/s and the measured power dissipation is about 75 mW.

Changing illumination condition can change the result of image segmentation algorithm and reduce the intelligent recognition rate. A novel color image segmentation method robust to illumination variations is presented. The method is applied to the skin segmentation. Based on the hue preserving algorithm, the method reduces the dimensionality of the red-green-blue (RGB) space to one dimension, while keeping the hue of every pixel unchanging before and after space transformation. In the new color space, the skin color model is established using Gaussian model. Experimental results show that the method is robust to illumination variations, and has low computational complexity.

We present a novel method for realizing double-image encryption algorithm by combining the images in different transform domains. Two original images are encrypted into two interim images by fractional Fourier transform and gyrator transform, respectively. The two encrypted images can be obtained by means of the addition and subtraction of the two interim images. This is defined as a double-image sharing scheme, in which the original images are encrypted into two parts. The original images cannot be recovered only with any one of the two interim images. Numerical simulation experiments demonstrate the validity of the algorithm.

We obtain high peak power pulses in megawatt range of the first (1181 nm), second (1321 nm), and third order (1500 nm) Stokes radiation from self-conversion of the 1067-nm laser radiation based on Nd:KGW laser. The maximum output energy of the first order Stokes laser is 35.3 mJ, which is to our knowledge, the highest reported energy in an intracavity Q-switched laser. The third order Stokes pulse is obtained in an intracavity Q-switched laser.

A non-destructive technique for subsurface measurements is proposed by combining light scattering method with laser confocal scanning tomography. The depth and distribution of subsurface defect layers are represented in term of scattered light intensity pattern, and three types of fused silica specimens are fabricated by different grinding and polishing processes to verify the validity and effectiveness. By using the direct measurement method with such technique, micron-scale cracks and scratches can be easily distinguished, and the instructional subsurface defect depths of 55, 15, and 4 \mu m are given in real time allowing for an in-process observation and detection.

A robust external cavity diode laser (ECDL) insensitive to mechanical vibration is built with an interference filter for selecting wavelength and a cat-eye reflector for light feedback. The free-running laser has a linewidth of 72 kHz. The laser frequency stability reaches 3×10^-12 at 1-s integration time in terms of relative Allan variance based on the saturation absorption spectrum.

We report the luminescence properties and decay profiles of Ce:YAlO₃, Mn:YAlO₃; and Ce,Mn:YAlO₃ crystals grown by Czochralski method. The spectroscopic properties show that both Mn²⁺ ions and Mn⁴⁺ ions exist in Mn:YAlO₃ and Ce,Mn:YAlO₃ crystals. The Mn²⁺ ions have a broad emission band of 60 nm in Mn-doped YAlO₃ crystal at 530 nm. The luminescence spectra also indicate that there is significant energy transfer between Ce³⁺ and Mn⁴⁺ in Ce,Mn:YAlO₃ crystal. Because of the energy transfer, the first decay component in Ce,Mn:YAlO₃ decreases from 24.5 to 10.8 ns, which is much faster than that of Ce:YAlO₃.

We present the investigation on LaF₃/porous silicon (PS) system that has properties of both the materials to be applied in photonics. Epilayers of LaF₃ are grown on PS under different anodization conditions using electron-beam evaporation (EBE). The characteristics of the LaF₃/PS system are analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and photoluminescence (PL). XRD confirms the polycrystalline nature of the LaF₃ film. Nearly stoichiometric growth of LaF₃ on PS is established by EDX. Such a thin LaF₃ layer grown on PS leads to a good enhancement of PL yield of PS. But with the increasing thickness of LaF₃ layer, PL intensity of PS is found to decrease along with a small blue-shift.

A novel structure with high surface enhanced Raman scattering (SERS) activity and bio-specificity as a SERS-based immuno-sensor (named as Raman reporter-labeled immuno-Au aggregate) is demonstrated and employed for protein detection. In each fabrication process, the features of those aggregates are obtained and characterized by ultraviolet-visible (UV-Vis) extinction spectra, transmission electron microscopy (TEM) images, scanning electron microscopy (SEM) pictures, and SERS spectra. Experimental results indicate that proper amounts of the reporter molecules can result in the moderate aggregation morphologies of gold nanoparticles. Compared with the previously reported method using Raman reporterlabeled immuno-Au nanoparticles, more sensitive SERS-based protein detection is realized with this novel immuno-sensor.

A method for local magneto-optical Kerr effect imaging based on a home-made scanning near-field optical microscope working in reflection mode is presented. Shear force detection is carried out by using a symmetric piezoelectric bimorph sensor, which provides an easy way not only for probe-surface distance control but also for imaging. Polarization-preserving fiber probes used as a local optical detector are fabricated with a heating-pulling technique and the probes' polarization properties are measured. Shear force topographic and near-field magneto-optical images of magneto-optical disk taken with the proposed method are shown.

We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equal amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the odd harmonic frequencies, and 2n+1 equal-amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the even harmonic frequencies. Then, we numerically simulate the spectra of 5, 7, 9, and 11 equal-amplitude spectral lines, respectively, which are also obtained in experiments with frequency separation of 30 MHz and flatness of better than 0.3 dB.

We review the dark decay of the electronic holographic phase grating before thermal fixing, and deduce the general analytic expression of the lifetime of thermal-fixed ionic holograms in the photorefractive crystal, by means of analogizing. Because the ions are optically inactive, the lifetime of thermal-fixed ionic holograms is only closely relate to the ionic decay rate which is determined by the conductivity of ionic species at a given temperature. We theoretically analyze and numerically simulate the influences on the lifetime of ionic grating from the crucial factors in the experiment and application. The results reveal that low temperature, low ion-concentration, and large grating spacing are advantages for extending the life of the thermal-fixed volume holographic phase grating in photorefractive crystal.

It is important for precise fabrication to research the material removal model of polishing. Simulation is done by computational fluid dynamics for fluid jet polishing (FJP). Numerical research and theoretical description for abrasive particles discrete system are taken by population balance modeling method, and experiments are taken to research the removal profile by vertical fluid jet polishing (VFJP). The results of experiment and simulation show that the removal profile of VFJP turns on a W-shaped profile. By analyzing the material removal mechanism of FJP that material is removed by particles impinging wear and wall movement erosion, the mathematical material removal model of VFJP is enduced. Comparing the mathematical material removal model with the experimental removal profile, it is found that the mathematical material removal model of VFJP is accurate.

A novel direct writing technique using submicron-diameter fibers is presented. This technique adopts contact mode in the process of writing, and submicron lines with different widths have been obtained. Experimental results demonstrate that the resolution of this technique can be smaller than the exposure wavelength of 442 nm, and 380-nm-wide line is achieved. In addition, the distribution of light fields in the photoresist layer is analyzed by finite-difference time-domain method.

A 128×128 elements cylindrical liquid crystal (LC) lens array with electrically controllable focal length is proposed. The cylindrical LC lens array uses transparent indium tin oxide (ITO) films as electrode, avoiding to affect the optical path operating in the voltage-off status. As the top electrode of the cylindrical LC lens array contacts with LC, the operation voltage root-mean-square (RMS) amplitude can be as low as 1.4 V and the response time is about 20-30 ms. The special optical focusing feature of the cylindrical LC lens array is got. And the focal length of this array is about 60-450 \mu m.

The stabilizing process of glass particle in water by optical trap using the pulsed counter-propagating Gaussian beams is investigated. The influence of the optical power and the particle dimension on the rate and time of the stabilizing process is simulated and discussed.

We demonstrate that a finite number of nano-slits can realize beam splitting and focusing of light by coating the metallic film surfaces with nonlinear Kerr medium. The numerical simulation shows that the beam splitting and focusing can be controlled by the incident light intensity. The splitting angle is quasi-periodically modulated by the incident light intensity, and the focusing length of forward propagating transmitted light decreases as the incident light intensity increases. These effects are explained by the surface plasmon polariton Bloch modes and self-focusing theory.

We present high resolution photoelectron energy spectra from multiphoton ionization (MPI) of Ar subject to laser pulses with wavelength of 400 nm, pulse duration of 35 fs, and maximum intensity of 5×10¹³ W/cm². Ionizations into Ar⁺ ²P_3/2 and ²P_1/2 channels are observed and distinct resonance structures are found in both ionization channels. The intensity dependence of the resonance structures is explained in terms of the mechanism of Freeman resonance, i.e., transient resonances of alternating current (AC) Stark-shifted Rydberg states at specific intensities within the laser pulse.

We present a new and efficient method for the design of dispersive multilayer by employing a particle swarm optimization (PSO) technique. Its mathematical background is given and an adaptive PSO is realized with computer code. Two practical designing tasks are solved with this method, and the obtained results are competitive compared with other published structures. The adaptive PSO method demonstrates its merits of fast convergence and powerful global search ability, and could be used as a valuable tool for the optical thin film design.