A practical two-stage double-pass structure using high concentration erbium-doped fiber and 1480-nm pump laser diode is suggested for a high power and broad bandwidth erbium-doped superfluorcscent fiber source. A considerable increase in output power and bandwidth extension is achieved by adding an unpumped fiber and a broadband fiber mirror to make the most of wasted backward amplified spontaneous emission as both pump and input light source simultaneously. Superfluorcscent fiber source with nearly 80-nm bandwidth and 28.6-mW output power is obtained experimentally.

Optical packet switching (OPS) technology can rapidly deliver the enormous network bandwidth and offer high-speed data rate and format transparency. In this paper we propose a novel architecture using alloptical tunable wavelength converters (TWCs) and fiber delay-lines (FDLs) to address the contention problem for OPS in wavelength and time domains. This architecture improves packet switching speed but significantly decreases the number of optical switches comparing with existing architectures. A simulation is also conducted to evaluate the performance of the architecture. The simulation results show that the packet loss probability of this architecture is lower than general architectures.

Based on the coupled-mode theory of fiber grating and codes theory, the design of an optical code division multiple access (OCDMA) encoder/decoder with stepped chirped fiber Bragg grating (SCFBG) has been proposed. The length of each uniform subgrating, the realization of encoding and decoding are provided. Numerical result is also presented and discussed.

Optical burst switching (OBS) is a promising optical switching technology. The burst assembly algorithm controls burst assembly, which significantly impacts performance of OBS network. This paper provides a new assembly algorithm, united assembly algorithm, which has more practicability than conventional algorithms. In addition, some factors impacting selections of parameters of this algorithm are discussed and the performance of this algorithm is studied by computer simulation.

A Yb-doped double-clad fiber laser is demonstrated with a measured power output of 10.6 W and a fundamental spatial mode. The optical-to-optical conversion efficiency is 44% and the slope efficiency is 86% closed to quantum efficiency of optical conversion. In our laser system, a D-shape (340 μm/400 μm) inner cladding Yb-doped fiber is used as the gain material within the Fabry-Perot cavity. Multimode diode pump radiation is injected into the cladding through an end facet of the composite fiber.

We demonstrate a technique for single transverse mode operation of high-power broad area laser diode (BAL). In the experiment, the HR mirror is used as an external cavity mirror and the grating is used as a wavelength selective component. By tiling the HR mirror and the grating, the number of transverse modes oscillating in the cavity can be limited and the spectral bandwidth of the laser diode can be reduced. A single-lobed near diffraction-limited laser beam with the beam divergence (FWHM) of 0.43°, the spectral line-width of 0.7 nm and the output power of 350 mW are obtained. With the feedback, the power density of the output laser beam is increased 6 times in comparison with the free running.

Diode-pumped passively Q-switched Nd:GdVO4/Cr^(4+):YAG lasers with a simple flat-flat cavity were demonstrated. The maximum average output power at 1.06 μm was 1.25 W. The highest peak power and pulse energy were 7.56 kW and 75 μJ, respectively, with the pulse repetition rate of 11.1 kHz and pulse width of 10 ns at the incident pump power of 8 W.

The effect of λ/2 SiO_(2) overcoat on the laser damage characteristics of HfO_(2)/SiO_(2) high-reflector (HR) coatings is investigated with 1-on-1 and N-on-1 laser damage test methods. The laser damage surface of 1-on-1 is analyzed by a step analyzer. The surface morphologies show that laser damage makes the coating damaged area protrudent and rough for HR coating without λ/2 silica overcoat, but concave and smooth for HR coating with λ/2 silica overcoat. The result of 10-on-1 multi-pulse irradiation on the same point of the coating shows that there is an energy density stage on the damage curve. If the laser energy density is within the range of the stage, HfO_(2)/SiO_(2) HR coatings with λ/2 silica overcoat will not be damaged more than 2 times for multi-shots, and the surface damages are very slight so that there is no impact on the coating performance. Another interesting result is that the energy density stage extends from the damage threshold to the point of about 3 times of threshold, which is similar to the effect of the laser condition on coating.

A novel technique termed nonredundant array scanning holography based on the principle of optical heterodyne scanning holography and the tomographic technique of coded aperture imaging is proposed. The system designed in terms of this technique codes an object optically and decodes its coded image digitally. It can realize optical tomograms of three-dimensional objects. It also has potentially practical value due to its compact structure. The computer simulations present the principle of the technique. Some experiments at the proof-principle level are performed to test the principle.

We demonstrate an angle-tuned signal-resonated optical parametric oscillator (OPO) with periodically poled lithium niobate (PPLN) pumped by a diode-pumped Nd: YVO4 laser. 1499.8 - 1506.6 nm of signal wavelength is achieved at 140℃ by rotating a 29-μm period PPLN from 0°- 10.22°in the x-y plane while keeping the pump wave vertical to the resonator mirrors. Two pairs of the signal and idler waves of the same wavelengths can be achieved symmetrically for each pair of angles of rotation with same absolute value and opposite sign. Theoretical analyses on angle-tuned PPLN-OPO with pump wave vertical to the resonator mirrors are presented and in good agreement with our experimental results. It is also found that all interacting waves in the cavity (not inside the crystal) are always collinear for PPLN-OPO with the pump wave vertical to the resonator mirrors while phase-matching is noncollinear within the crystal.

After passing through four dispersive-prisms, the Q-switched Cr:LiSAF laser with broad frequency band is focused into carbon disulfide (CS_(2)) to produce backward stimulated Brillouin scattering (SBS). Our experimental results and illustrative analysis have shown that this frequency-dispersive method can efficiently reduce the broad-band SBS intensity threshold, compress its pulsewidth, and improve the beam quality.

Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton’s peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.

The purpose of this paper is to deduce an analytical expression for the violation of Bell’s inequality by quantum theory and plane trigonometry, and expound the violation and maximal violation of the first, second type Bell’s inequality in detail. Further, we find out the sufficient conditions for the region in which Bell’s inequalities are violated.

Resonant cavity enhancement (RCE) typed optical detector and modulator which operating at wavelength band of 1.06 μm is reported. The peak quantum efficiency of detector is reasonably high as 50% without bias, and the photocurrent contrast ratio of modulator is 3.6 times at -3.5 V as compared to 0 V. The incident angle dependence of RCE device’s photoelectric response is investigated carefully.

An optimum design of static Fourier-transform spectrometer based on Savert prisms is presented in this paper. A new method of increasing path difference and resolution of spectrometer is given. When the angle between the crystal optical axis of the first Savert prism and the incident interface is 58°and the angle between the crystal optical axis of the second Savert prism and the incident interface is 28°, the maximum path difference will be 0.63 mm, the maximum resolution will be 15.8 cm^(-1), and the whole field-of-view will reach 6°.

In this paper, laser Doppler reference optical technique is studied, and an optical system with high resolving power which is applied to longitudinal displacement measurement of complicated 3D object is brought forward. Structure of the measuring optical head is designed reasonably. The experiments prove that the new-type reference optical system can achieve the outline loss measurement of object with the relative error of 0.3%.

The cavity enhanced absorption technique is applied to N2O detection around 2.86 μm using a continuouswave color center laser. A high-finesse triangular ring cavity is used in this technology. Transmission through the cavity is obtained by jittering the cavity-length with a piezo on one of the cavity mirrors. A minimum detectable absorption coefficient of 2 * 10^(-6) cm^(-1) is achieved with a mirror reflectivity of 99.24%, corresponding to a N_(2)O detection limit of 600 parts per billion.

When femtosecond laser pulses interfere with chirped femtosecond laser pulses in As_(2)S_(3) fiber, a chirped fiber grating is formed. An analytical expression is given to describe the chirped grating, and its Bragg reflectivity is calculated. Because of the high photosensitive effect of As_(2)S_(3) material, the chirped fiber grating has a wide Bragg reflective spectrum and high reflectivity by choosing proper parameters. This indicates that the chirped fiber grating can be used as a stretcher in the femtosecond chirped pulse amplification (CPA) system.

The influence of circular aperture on the intensity of high-order harmonic generation (HHG) with intense femtosecond laser pulse was studied both experimentally and theoretically. The intensity variety of HHG with the diameter of circular aperture was observed in pulsed Ar gas. The result was discussed and interpreted in terms of the theory of Hankel transform. It is found that using the Gaussian beam truncated by an aperture could enhance the conversion efficiency of HHG at certain conditions.