The diffraction efficiency spectrum of PQ-PMMA volume Bragg grating (VBG) depends on the absorption coefficient and refractive index modulation of PQ-PMMA. The peak diffraction efficiency can shift more than 0.2 nm from the intended written wavelength.

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A tunable dual single longitudinal modes laser is built using two homemade PQ-PMMA volume Bragg gratings (VBG) as the wavelength selecting and spectral narrowing elements. The laser can achieve the wavelength tunning range more than 10 nm without damage the PQ-PMMA VBGs.

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We present the modeling of dipolar exciton ground state in AlGaAs asymmetric coupled quantum wells in an external electric field induced two-dimensional electrostatic trap. It is shown that a stable spontaneous emission can be obtained where its radiative lifetime approaches 50 ps.

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A continuous-wave mode-locking laser system via positive cascaded second-order Kerr lens (CSKL) at 1063 nm was demonstrated. An average power of 3.49 W is obtained under 19.5 W diode power at 808 nm. The pulse repetition rate, and the pulse duration are 175.44 MHz, and 18 ps, respectively.

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In this paper, a simulation program using Non- Equilibrium Greens function formalism with electron-phonon (acoustic and polar optical phonon) is developed for studying carrier transport with energy relaxation. The result shows thatthe carrier energy of the current density would be broadened after applying the scattering. The result suggests that a proper scattering consideration should be considered in most quantum transport model.

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We report the study of the finite-beam　Bragg diffraction behavior of an electro-optic volume grating made of a PPLN crystal. The experimental observations show that the diffraction mode pattern and diffraction efficiency of the PPLN EO Bragg device are closely related to the interaction beam size and applied voltage.

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When the interaction of orthogonally polarised modes with the active medium occurs, the low-frequency relaxation oscillation for antiphase mode will be generated. This work demonstrates the dynamics corresponding to pump modulation frequency approaching to this low frequency. The relationship of average frequency of chaotic signal between in-phase and anti-phase oscillation were studied.

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We used the nonlinear Schrödinger equation to model the process of continuum generation using multiple thin plates. The result is compared with experiments done with an 800 nm femtosecond laser pulse.

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Graphene thin-films were prepared by CVD method with different layers and measured by Z-scan technique. Results showed that nonlinear absorption was due to saturation of single photon absorption. Under the intensity of 21.3 GW/cm2, 1- and 8-layer graphene showed the nonlinear absorption coefficient α(I) of 1.342 and 0.043 (10^8 m-1).

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In this study, GaN-based photonic quasi-crystal surface emitting lasers (PQCSELs) were fabricated and analyzed. The device for Γ5 mode exhibited the lowest threshold pumping energy density of 4.6 mJ/cm2. The tendency of calculated gains was consistent with the experiment results. We concluded that the PQCSEL had the opportunity to acquire lower threshold energy density than conventional PCSEL if it operated at special band-edge mode.

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Self-phase modulation (SPM) and group delay dispersion (GDD) managed erbium-doped fiber laser (EDFL) mode-locked with few-layer graphene nano-sheet is demonstrated to optimize the soliton compression at a negative GDD region.

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The characteristic difference between forward- and backward-pumped ytterbium-doped fiber laser is investigated. In the forward pumping scheme, the over-pumping power can be reused in the next cycle to enhance the gain in the fiber cavity. Therefore, higher output power and slope can be obtained.

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In this paper, we demonstrated the chirped pulse amplification (CPA) of a high-power ytterbium-doped fiber amplifier at wavelength of 1064 nm without a stretcher. The all-normal dispersion (ANDi) passively mode-locked fiber laser is used to generate highly chirped seed pulse. Further, the compressed-pulse was frequency doubled by a type-I critically phase-matched (CPM) Lithium Triborate (LBO) crystal. With 370 mW of fundamental light, we can generate 88 mW of green output (λ= 532 nm) with conversion efficiency of 23%.

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The silicon carbide saturable absorbers with varying C/Si composition ratios are employed to passively mode-lock the fiber laser for compressing the pulsewidth from 400 fs to 360 fs with a time-bandwidth product of 0.317 when varying the SixC1-x from the stoichiometric to C-rich condition.

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We used Z-scan without aperture technique to measurement the nonlinear optical absorption properties of gold-nanoparticle films. We use sample is 3-Mercaptopropionic acid (MPA). Those gold-nanoparticle films was comprised by diameter 12nm with two layers(MPA1) and three layers(MPA2). And those samples’ UV-Visible absorption characteristics show in Figure. Then we studied those samples at off-resonant wavelengths and the result of fitting data are showing in table . Our laser light source is mode-locked femtosecond Ti:sapphier laser(790nm,120fs).

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We reported that spectrally-resolved two-beam coupling [1] using a mode-locked Ti:sapphire laser produces reliable measurements of the nonlinear responses of fused silica. The nonlinear index of refraction of fused silica n_2=3.18×〖10〗^(-20) m2/W. Figures 1, 2 show experiment results on fused-silica at 780 and 800nm, respectively.

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