Research on immunosensor based on porous silicon

Porous silicon is functionalized using thermal oxidation and silanization. The HYSA antibodies are immobilized to the porous surface in this paper. The changes in the reflection spectrum and photoluminescence spectrum are investigated when BSA are attached to the PS surface. The result shows that the luminescence peak of PS disappears. After the antigen- antibody reaction, the higher light emission is observed and the reflection spectrum also red shifts. Therefore, this research lays a foundation for the development of sensitive label-free optical immunosensor.     

Diode-pumped double passively Q-switched Nd:GdVO4 laser

Through using both Cr^4＋：YAG and GaAs saturable absorbers, a diode-pttmped double passively Q-switched Nd：GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.     

Study of wavelength demultiplexer based on two-dimensional photonic crystals

A wavelength demultiplexer based on two dimensional photonic crystal waveguides is proposed. By using the finite difference time domain （FDTD） method and plane wave extension （PWE） method, the transmission spectra and the distributions of mode field are obtained, and the wavelength demultiplexer has been synthesized. The characteristics of the device are obtained.     

Study of a displacement sensor based on transmission varied-line-space phase grating

A displacement sensor based on transmission varied-line-space （VLS） phase gratings is proposed. The relationship be-tween the properties of the sensor and the parameters of VLS is discussed. Compared with the displacement sensor manu- factured by the reflective VLS grating, this type of sensor contains a grating with simpler structure and high diffraction efficiency. It also has good stability with the change of temperature.     

Research on fault location technology based on BP neural network in DWDM optical network

BP neural network is introduced to the fault location field of DWDM optical network in this paper. The alarm characteristics of the optical network equipments are discussed, and alarm vector and fault vector diagrams are generated by analyzing some typical instances. A 17 × 14 × 18 BP neural network structure is constructed and trained by using MATLAB. By comparing the training performances, the best training algorithm of fault location among the three training algorithms is chosen. Numerical simulation results indicate that the sum squared error （SSE） of fault location is less than 0.01, and the processing time is less than 100 ms. This method not only well deals with the missing alarms or false alarms, but also improves the fault location accuracy and real-time ability.     

Frequency stabilization in FBG external cavity semiconductor laser based on acetylene absorption method

A frequency-stabilized 1.53 μm FBG external-cavity semiconductor laser by using acetylene absorption is presented and its basic principles are introduced. Graded refractive index fiber and pigtailed fiber are used in the absorption air chamber to enhance the coupling stability. The impact of the background power is eliminated by using the third-harmonic mode-locking technique. A lock-in amplifier is utilized to ensure that the output laser wavelength is locked at the C2H2 absorption line of 1530.37 nm. The frequency stability reaches 10^-8 within 24 h.     

Theoretical research on light propagation in W-type single-mode fiber

We give the characteristic equation of a W-type fiber by solving Maxwell＇s equations along with boundary conditions at the interfaces. The cutoff condition of the fundamental mode is examined, and a novel W-type fiber working in S-band is designed.     

Numerical analysis on heat transfer of laser diode module by equivalent electrical network method

Because it is complex and inconvenient to use the common temperature field calculating method and experiment method, for arialyzing heat transfer properties of laser diode module （LDM）, an equivalent electrical network method is presented in this paper. Simulation results show that the temperature stability is closely related to ambient temperature, heat sink, LDM current and TEC current. Ambient temperature and TEC controller are the dominant terms effecting on temperature control in practice,     

Theoretical analysis of radiation-balanced double clad fiber laser

Recently,double clad fiber lasers with an output ofkilo-watt power have been reported[1].Thermal prob-lems such as thermal stressinducedfracture,decreasingof quantumefficiency andthermal lens effect are seriousinthis kind of high powerfiberlaser[2].In1995 ,fluores-cence cooling in Yb doped ZBLANP(ZrF4-BaF2-LaF3-AlF3-NaF-PbF2) glass was realizedfor thefirst ti me[3].Consequently,a section of Yb doped ZBLANP glass fi-ber laser was cooled from298 Kto 282 Kin the vacu-um[4].According t…     

Study of a middle-wavelength infrared athermalized optical system

For cooled 320 × 240 detector with staring focal plane array, a novel middle infrared athermal optical system is presented. The system is composed of 5 spherical lenses. The materials of lenses are silicon and germanium. The optical parameters and modulation transfer function （MTF） are investigated. The system has the diffraction limited image quality and stable image plane from -30 ℃ to 70 ℃. The characteristic parameters of the system are as follows：flnumber of 4, cold shield efficiency of 100%, spectrum region of 3.7-4.8 μm and transmissivity of 80%. The system has the merits of simple structure, low price, and it is easy to machining.     

An all-optical remote controlled X-Nor logic using soliton pulse

We propose a new method to perform an ultra high speed all optical remote controlled X-NOR logic operation at a very long distance by exploiting the interaction ofhypersecant optical soliton pulses （HOSP）. To implement such logic operation, three HOSPs maintaining a particular condition are introduced into an optical fiber where they interact with each other. Two of them carry the input of the logic operation with the constant triggering of other HOSP.     

Combined optical fiber interferometric sensors for the detection of acoustic emission

A type of combined optical fiber interferometric acoustic emission sensor is proposed. The sensor can be independent on the laser source and make light interference by matching the lengths of two arms, so it can be used to monitor the health of large structure. Theoretical analyses indicate that the system can be equivalent to the Michelson interferometer with two optical fiber loop reflectors, and its sensitivity has been remarkably increased because of the decrease of the losses of light energy. PZT is powered by DC regulator to control the operating point of the system, so the system can accurately detect feeble vibration which is generated by ultrasonic waves propagating on the surface of solid. The amplitude and the fre- quency of feeble vibration signal are obtained by detecting the output light intensity of interferometer and using Fourier transform technique. The results indicate that the system can be used to detect the acoustic emission signals by the fre-quency characteristics.     

Linearity optimization of edge filter demodulators in FBGs

A kind of electric circuit is improved to optimize the linearity of edge filter demodulators in FBG .By using a logarithm amplifier and an extraction operation, the linear range of optimized edge filter demodulators has been broadened effectively, and the requirement of optical filter＇s linear range has been reduced. Theoretical analyses and the simulation results indi-cated that the linear range of optimized edge fdter demodulator＇s covers the whole transition region of the edge filter, while a strict linearity of the optical filter is not necessary.     

Monte Carlo simulation for the sputtering yield of Si3N4 thin film milled by focused ion beams

The sputtering yield of the Si3N4 thin film is calculated by Monte Carlo method with different parameters. The dependences of the sputtering yield on the incident ion energy, the incident angle and the number of Gallium （Ga） and Arsenic （As） ions are predicted. The abnormal sputtering yield for As at 90 keV occurs when the incident angle reaches the range between 82° and 84°.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave （CW） 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd： YVO4 and using LBO as the intra-cavity SHG crystal. With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457 nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the output power is better than 1.2% for 8 h continuously working.     

Study of a high-temperature and high-pressure FBG sensor with Al2O3 thin-wall tube substrate

A fiber Bragg grating （FBG） high-temperature and high pressure sensor has been designed and fabricated by using the Al2O3 thin-wall tube as a substrate. The test results show that the sensor can withstand a pressure range of 0-45 MPa and a temperature range of-10-300 ℃, and has a pressure sensitivity of 0.0426 nm/MPa and a temperature sensitivity of 0.0112 nm/℃     

Quality improvement of the dual-wavelength signals in DLOB via power equalization

The data packet buffeting can be implemented in dual loop optical buffer （DLOB） through cross-phase modulation （XPM） between the control signal and the data packets. However, the output equality of dual wavelength signals will degrade due to the unbalanced gain and phase shift. This problem can be resolved by power oqualizafion using the saturation characteristics of SOA. The data packets with 2.5 Gb/s can be buffered in DLOB for 16 cycles corresponding to 16.5 μs.The extinction ratio of the output packet is 8 dB while the S/N is 8.1 dB.     

Coupling characteristics between five-layer slab wave-guides including left-handed materials

To obtain the coupling characteristics between slab wave-guides including left-handed material, we modify the coupled wave equations by using Maxwell＇s equations. First, we obtain new-coupled wave equations and new-coupling coefficient. Second, the coupling between two identical five-layer slab wave-guides where their cores are left-handed material, but their claddings are right-handed materials is studied. The coupling coefficient for even TE mode which is more complex than that of the riglt-handed material slab wave guides, is obtained.     

Design of low-confinement-loss and highly birefringent index-guiding photonic crystal fibers

We present a systematic scheme to achieve both high birefringence and low confinement loss in index-guiding photonic crystal fibers （PCFs）, using a structurally-simple PCF with finite number of air holes in the cladding region. By increasing the size of the outermost-ring air holes in the cladding region, highly birefringent PCFs with low confinement loss can be successfully achieved. The design strategy is based on the fact that the modal birefringence of PCFs is dominated by the inner-ring air holes in PCF, which is verified by a full-vector finite element method with anisotropic perfectly matched layers. Numerical results show that modal birefringence in the order of 10-3 and confinement loss less than 0.1 dB/km can be easily realized in the proposed PCF with only four rings of air holes in the cladding region. We expect that such fibers will be much easier to be fabvicated than those with more air holes in the cladding region.     

Studies of the correction for phase diverse speckle

Phase diverse speckle is a novel kind of imaging technique and can be used to overcome image degradation from unknown phase aberrations, such as atmospheric turbulence. The wave-front phase expanded on the Zernike polynomials is esti- mated from a pair of images (in the focal and out of focus planes). In this paper the principle of PDS is analyzed, and genetic algorithm is used as the iterative algorithm to simulate some characteristics, such as the influence of Zernike polynomials’ mode, amplitude of turbulence on the phase estimation. Thus, a new method for recovery of images is explored.