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.     

Effect of Sb2O3-doped on optical absorption of ZnO thin film

ZnOthinfil mis a compound semiconductive materialof hexagonal Wurtzite structure.It has been widely ap-pliedto manyareas suchastransitive conductive windowmaterials , ultraviolet detectors , LEDs and LDs lumi-nance devices ,etc ,because of its unique electrical andoptical properties , good chemical stability, high activeenergy and melting point ,abundant ,cheap and nontox-ic source,and relatively lowpreparing temperature[1-4].Recent researches showthat the properties of ZnOthinfil mchange o…     

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/℃     

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.     

Manufacture and characteristic analysis of YVO4 laser polarized prisms

A YVO4 crystal Gland-Foucasult prism is manufactured. The relationships between prism structure angle and view field angle are studied with different wavelengths. The results show that the prism with the structure angle of 2 8.180 has a good extinction ratio and the transmission characteristic in both visible and near-infrared regions.     

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°.     

Laser-diode pumped Nd: GdVO4 ultraviolet laser with LBO frequency tripling

We have demonstrated a laser-diode pumped Nd.GdVO4 extra-cavity frequency tripling ultraviolet laser with a LBO crystal in this paper. Under the acousto-optic （A-O） Q-switched operation, we have obtained 355 nm ultraviolet laser,with pulse width of 25 ns and pulse repetition rate of 20 kHz. By using a type Ⅰ non-critical phase-matched LBO crystal, the SHG output power of 822 mW is achieved at the incident pump power of 16 W. The output power of 355nm UV laser is 260mW with a type Ⅱ phase-matched LBO crystal,and the conversion efficiency （1 064 nm-355 nm） is 5.9 %. The power stability of 355 nm laser is 1.7% in 1 h.     

Monte Carlo simulation for the sputtering yield of Si_3N_4 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 82o and 84o.     

Thermal lens measurement of a LD end-pumped Nd：GdVO4 laser with stable resonator by a slit-scanning method

Recently,some feasible ways have been put forwardsto determine the thermal focal lengthfTof gain mediumin end-pumped solid-state laser ,such as CCD-photo-graph[1]and stable cavity condition[2].However ,thismethodinvolves the complicated experi mental setup andcannot be directly applied for high power pump due tothe saturation effect of CCD.Stable cavity conditionmethodis relatively si mple,but since there is no laseroutput when the stable cavity just turns into unstablesome parts of energy o…     

Modeling laser-diode-pumped Tm3+-doped fiber amplifiers

A theoretical model is developed for the laser-diode-pumped Tm³⁺-doped fiber amplifier, and a set of ordinary differential equations (ODEs) governing the dynamics of dual-wavelength pumping scheme (1.4μ+1.56μ) based on the rate equations and propagation equations was established. The relationship between the spectra gain and pump power was described and analyzed by numerically solving the ODEs. Spectral gain as a function of longitudinal position along the fiber was given to optimize the fiber length; spectral gain per unit length, and fractional inversion were used to explain the gain shift property of TDFA. The theoretical results agree well with the experimental data. Received 28 March Supported by China Scholarship Council, Natural Science Foundation of Shandong Province of China (grant no. Y2003G01 and Y2002G06), Research Fund for the Doctoral Program of Higher Education of China (grant no. 2002022048     

Teleportation of an arbitrary unknown N -qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers（M 〈 N） is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home- Zeilinger （GHZ） state and N-M non-maximally entangled Einstein-Podolsky-Rosen （EPR） pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Passive mode locked diode-pumped Nd:GdYVO4 laser with a GaAs absorber

A passively Q-switched mode-locked Nd：GdYVO4 laser is successfully demonstrated by using a piece of GaAs crystal grown at low temperature as the passively saturated absorber and the output coupler. Fundamental properties of the Nd： GdYVO4 laser are investigated. The maximum average output power of 3.5 W is obtained by using plainsphere when the incident pumping power is 10 W, which corresponds to an optical-optical coversion efficiency of 35%. The threshold power for the Q-switching mode-locked is 1.2 W. The maximum average output power of 1.72 W is obtained by using GaAs when the incident pumping power is 10 W, mode-locked pulse train with a repetition rate of - 113 MHz is achieved. At the incident laser pumping power of 7 W, the modulation depth is 100%.     

Deposition of GaN thin film on ZnO/Si by DIBD method

The GaNis a semiconductor material witha widefor-bidden band(Eg=3.36eV).It has many unique advan-tages such as high electron drift velocity,small dielectricconstant,goodthermal conduction et al.It is a favorablematerial for making electric devices with hi…     

High-power superfluorescent source of Yb^3＋ -doped double-cladding photonic crystal fiber

A new type of high-power broadband superfluorescent source of Yb^3＋ -doped double-cladding photonic crystal fiber is reported experimentally, which is pumped at 976 nm by a high-power laser diode with the end-coupling method. We have obtained a smooth broadband output of superfluorescence The maximum output power is 1.649 W with a slope efficiency of 56.7%. The 3 dB bandwidth is 22.4 nm To the best of our knowledge, this is the first report about SFS with such high output power of 1.649 W.     

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.     

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.     

Characteristics of surface and interface for ITO/PTCDA/p-Si thin film device

Recently,organic semiconductor thin fil ms becomemore and morei mportant in the application of electron-ics and photoelectronics because of their unique electron-ic and optical properties[1-4].One of main advantages oforganic thinfil ms as electronic mate…     

Acoustic anisotropy of piezoelectric LiNbO3 crystals and its application in integrated acousto-optical tunable filters

We use Joness matrix method and the global optimal method to investigate the propagation characteristic of surface acoustic wave（SAW） for X-cut single crystal Lithium Niobate（LiNbO3 ）. As an application, a novel integrated acousto-optical filter,which allows to minimize the dimension of AO cells and suppress side-lobes,was designed on the base of LiNbO3 crystal.     

Transport and electroluminescence mechanism in Au/（Si/ SiO2）/P-Si film

Following the development of information technolo-gy,it has been a tendency to take the place of electronby photon as a carrier of information,since photons canmove thousands ti mes faster than electrons ,which cani mprove the rate of communication.Silico…