Y. X. Xia

Shanghai Jiao Tong University, Shanghai, Shanghai Shi, China

Are you Y. X. Xia?

Claim your profile

Publications (44)90.63 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose and experimentally demonstrate the propagation of slow/fast light in an erbium-doped fiber (EDF) using mutually modulated cross-gain modulation. The group velocity of the light signal can be manipulated by the effect of gain cross-saturation modulation by a saturating light at an arbitrary wavelength in the gain bandwidth of the EDF. The ultraslow propagation with a small group velocity of 5.6 × 10⁻³c (c is the light speed in free space) and superluminal propagation with a negative group velocity of -1.1 × 10⁻³c has been observed under different modulation phases.
    Optics Letters 06/2011; 36(12):2185-7. DOI:10.1364/OL.36.002185 · 3.39 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The supercontinuum generation has been obtained in short conventional dispersion-shifted fiber using the femtosecond pulses from a passively mode-locked erbium-doped fiber laser. In the experiment, the supercontinuum spectrum of >300 nm has been observed by injecting 70-fs pulses into a several-meter dispersion-shifted fiber. The simulation of the evolution in the fiber shows that spectral broadening arises from soliton dynamics when pumping using femtosecond pulses in the anomalous group velocity dispersion regime of the fiber.
    Laser Physics 06/2010; 20(6):1459-1462. DOI:10.1134/S1054660X1011006X · 1.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A period-chirped long-period fiber grating (CLPFG), using ordinary multi-mode fiber (MMF), for broadband mode conversion (60 nm bandwidth of coupling efficiency >90%) has been proposed. Through using such a MMF-CLPFG, a broad-spectrum pulse can be converted into LP 02 for femtosecond pulse distortion-free delivery in MMF. The simulation shows that the pulse suffers less nonlinear distortion than that in a single-mode fiber. In addition, the negative pre-chirp introduced by MMF-CLPFG can offset the linear and positive SPM-induced frequency chirp and thus compress the pulse. Using this scheme, an initial 18 kW peak power 75 fs pulse distortion-free delivery in MMF has been numerically demonstrated.
    Journal of Modern Optics 03/2010; 57(6):485-491. DOI:10.1080/09500341003714130 · 1.17 Impact Factor
  • Source
    C Q Yu, H Wang, S Q Xiao, Y X Xia
    [Show abstract] [Hide abstract]
    ABSTRACT: Lateral photovoltaic effect (LPE) observed on the metal films is unusual because it violates a principle that the LPEs are always observed on the surface of a semiconductor. Compared with early studies, we have realized an obvious metal film LPE in a metal-semiconductor (MS) structure. By further arguing with experimental results, this work also intensively elucidates many features of LPE which the early models never touched upon. All the data and analyses in this study indicate that metal side LPE in MS structure has some natural superiorities to the semiconductor side LPE and may open many exciting opportunities for realizing multifunctional devices.
    Optics Express 11/2009; 17(24):21712-22. DOI:10.1364/OE.17.021712 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We experimentally demonstrate a simple-structure but efficient multiwavelength erbium-doped fiber laser based on nonlinear polarization rotation assisted by four-wave-mixing (FWM). Based on the com-bination of these two nonlinear mechanisms contributing to intensity-dependent loss to alleviate mode competition, the stable multiwavelength operation at room temperature can be realized in a length of dispersion-shifted fiber. We achieved up to 38-wavelength generation with a spacing of $0.4 nm in the laser. In addition, through tuning the birefringence fiber filter, the lasing wavelength can be accu-rately tuned in the free spectrum range.
    Optics Communications 07/2009; 282(14). DOI:10.1016/j.optcom.2009.03.070 · 1.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We propose and demonstrate a novel switchable multiwavelength erbium-doped fiber laser with a overlapping linear cavity, which is formed by a dual-section Lyot–Sagnac filter and three fiber Bragg gratings (FBGs). Taking advantage of the high extinction of the Lyot–Sagnac filter, independent controlling of the different wavelength losses and the spatial hole burning in the overlapping linear cavities, with this structure we realize stable switchable multiwavelength laser emission at room temperature. An output signal to background noise ratio of 43 dB and less than 3 dB fluctuation on output power were observed for all wavelength switching cases.
    Journal of Modern Optics 01/2009; 56:145-148. DOI:10.1080/09500340802531216 · 1.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have built a complete Raman detection system for multi-trace-gas diagnosis, which is suitable for analyzing the dissolved gases in electric power system. In the system, a high-sensitivity CCD device connected to a spectrometer is used as the detection unit of the Raman system. A near-confocal cavity is used for improving the detection sensitivity of the system. In the effective spectral range of about 570–710nm, Raman spectra of eight typical gases are achieved by using this Raman system. The detection limits for different gases have been obtained: 126ppm for CO2, 21ppm for CH4, 63ppm for C2H4, 42ppm for C2H2, 96.6ppm for H2. The detectability of the system satisfies the requirements of gas diagnosis in power transformer.
    Applied Physics B 11/2008; 93(2):665-669. DOI:10.1007/s00340-008-3170-8 · 1.63 Impact Factor
  • Source
    Z. Y. Fan, Li Zhan, Xiao Hu, Y. X. Xia
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a new explanation of the extraordinary optical transmission through subwavelength hole array in metal films. By using the classical coupled-wave theory, we analyzed the coupling process between light and the surface plasmons wave on metal films with hole array. The analysis shows clearly the physical mechanism of extraordinary optical transmission. The calculation demonstrates that, instead of energy flux directly passing through the holes, the electromagnetic modes could exchange energy by overlapping the evanescent fields under the assistance of hole array. The periodicity of the array provides the momentum-matching condition to present the transmission peaks. The theory exhibits a good agreement with the experimental results reported in every detail.
    Optics Communications 11/2008; 281:5467–5471. DOI:10.1016/j.optcom.2008.07.077 · 1.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Though separate studies on the individual properties of photovoltage and magnetoresistance (MR) have made much progress, work integrating the two phenomena into one kind of structure has not been reported so far. This study combines MR and lateral photovoltage (LPV) in a magnetic oxidized film Co3Mn2O deposited on an n-type Si substrate with a native ultrathin SiO2 surface by sputtering. The effective resistance shows a marked transition for temperature around 240 K. Both negative MR {MR = [R(H) -R(0)]/R(0) × 100%} of - 11% at 4.2 K and a large positive MR of 70% at 300 K at a magnetic field of 6 T were observed. This phenomenon can be explained by the conducting channel switching from the upper film to the Si inversion layer. Under the nonuniform illumination of a laser beam, the LPV shows a high sensitivity to the spot position on the Co3Mn2O film plane. The current–voltage (I–V) characteristic of the Co3Mn2O/SiO2/Si metal–oxide–semiconductor (MOS) structure exhibits rectifying I–V behavior, which suggests that the lateral photoeffect (LPE) can be interpreted in terms of the metal–semiconductor (MS) junction that exists between the magnetic film and silicon substrate. When an external magnetic field is applied perpendicular to the film, the LPV shows a monotonic increase with increasing magnetic field. The variation of LPV reaches 93.2% at 2 T. This intriguing effect may be due to the Lorentz force acting on the photo-generated carriers.
    New Journal of Physics 09/2008; 10(9):093006. DOI:10.1088/1367-2630/10/9/093006 · 3.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrated a high-power single-longitudinal-mode (SLM) all-fiber laser. In the cavity, a fiber Bragg grating is used to select the appropriate wavelength at 1565 nm, and a fiber ring is incorporated to act as a Fabry-Perot resonator, which greatly reduces the longitudinal-mode density. Meanwhile, an unpumped erbium-doped fiber serves as a saturable absorber to ensure the SLM operation. Finally, a high-power SLM fiber laser producing as high as 867-mW output power has been experimentally demonstrated.
    IEEE Photonics Technology Letters 07/2008; 20(11-20):879 - 881. DOI:10.1109/LPT.2008.922332 · 2.18 Impact Factor
  • Source
    X. X. Yang, Li Zhan, Y. X Xia
    [Show abstract] [Hide abstract]
    ABSTRACT: We have demonstrated a simple method to achieve a high-power single-longitudinal-mode all-fiber ring laser by employing two Sagnac loop filters. In the ring cavity, a high-birefringence Sagnac loop filter is incorporated to limit the affiliated longitudinal modes, and another Sagnac loop filter with unpumped erbium-doped fiber serves as a saturable absorber to ensure single-longitudinal-mode operation. Using such a simple configuration, a single-longitudinal-mode fiber laser with scalable output power of 360mW has been demonstrated.
    Optical Engineering 06/2008; 47(6):065001. DOI:10.1117/1.2938835 · 0.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we demonstrate a new architecture of a self-seeded multiwavelength Brillouin-erbium laser by using a nonlinear optical-loop mirror and a nonlinear amplifying-loop mirror (NOLM-NALM). A stable operation of 61 Brillouin-Stokes lines with a 0.08-nm spacing was obtained and the laser exhibited satisfied the flatness of the output spectrum with a low-threshold pump power. It is shown that the four-wave mixing (FWM) contributes to the generation of high-order Brillouin-Stokes and anti-Stokes and, consequently, results in the increase of the Stokes number and the reduction of its peak power.
    Laser Physics 04/2008; 18(4):442-445. DOI:10.1134/s11490-008-4015-1 · 1.03 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a transient lateral photoeffect (LPE) in thin metallic Co films deposited on n-type Si substrates with native SiO(2) surfaces. Under the nonuniform irradiation of a laser beam, the lateral phtovoltage (LPV) shows high sensitivity to the laser position in the metal film plane. This effect can be interpreted by the metal-semiconductor (MS) junction formed between metal and semiconductor. The LPV depends significantly on the thickness of Co film. The position sensitivity shows a peak value of 42.6 mV/mm for Co(2.8mn)-SiO(2)-Si and decreases greatly with the increase of the Co film thickness. We explain that by the shorting effect of the metallic film.
    Optics Express 04/2008; 16(6):3798-806. DOI:10.1364/OE.16.003798 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Position-sensitive detectors (PSDs) founded on p–n junctions or metal–semiconductor (MS) junctions have been studied for many decades. This work reports a novel PSD based on Co–SiO2–Si metal–oxide–semiconductor (MOS) structures. Different from the traditional MS devices where the results were mostly obtained at a given surface (semiconductor side), our MOS devices show better results for both the metal and semiconductor sides (the corresponding measurement methods are referred to as the obverse mode and the reverse mode). We systematically investigated the topographies of Co films, the transverse Schottky barrier (SB) I–V characteristics, and the Co film thickness dependence of the position sensitivities measured in both modes. The maximum sensitivities, which occurred at 28 Å, are 42.64 and 51.98 mV mm−1 for the obverse and reverse modes, respectively. The highest sensitivities measured in both modes are much larger than those of the classical MS devices and this can be attributed to the thin insulating SiO2 layer between the Co film and the Si substrate. The position sensitivity measured in the obverse mode decreases greatly with increasing Co film thickness. We explain this by the shorting effect of the metallic film.
    New Journal of Physics 03/2008; 10(3):033018. DOI:10.1088/1367-2630/10/3/033018 · 3.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Both lateral photovoltage (LPV) and positive magnetoresistance (MR) are observed in Co/Mn/Co/c-Si structure. The LPV shows a large sensitivity of 10 mV mm-1 as a laser spot is moved on a film surface. An apparent positive MR of 2.8% (at 4.2 K) is also found in the structure and is explained based on the enhanced scattering at the interface. The LPV is discussed in terms of the metal-semiconductor junction that exists between the film and the Si substrate. The combined properties add functionality to the single magnetic or optic property and facilitate matters for dual role devices that are both sensitive to the light and magnetic field.
    Journal of Physics D Applied Physics 03/2008; 41(5). DOI:10.1088/0022-3727/41/5/052003 · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have demonstrated a tunable multiwavelength self-seeded Brillouin-erbium fiber laser (BEFL) without externally Brillouin pumping. In this scheme, the stable multiwavelength comb can be produced within a ∼45-nm wavelength tuning range through adjusting the polarization controllers (PCs) in a high-birefringent Sagnac loop mirror. The generation of ∼200-line Stokes comb has been achieved by adjusting PCs under bidirectional pumping of two laser diodes, which is the largest wavelength number to the best of our knowledge. The effect of 980 nm pump power on the multiwavelength generation was also investigated.
    Optics Communications 02/2008; 281(3):452–456. DOI:10.1016/j.optcom.2007.09.046 · 1.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Magnetic and transport properties were investigated in metal-oxide-semiconductor structures of Co3Mn2O/SiO2/Si prepared by the dc magnetron sputtering technique. Magnetic studies reveal that Co3Mn2O is a granular film consisting of CoO, MnO, Co and Mn. The effective resistance shows a marked transition for temperature at around 240 K. Both negative magnetoresistance {MR = [R(H) − R(0)]/R(0) × 100%} of −11% at 4.2 K and a large anomalous positive magnetoresistace of 70% at 300 K at a magnetic field of 6 T were observed. These phenomena can be explained by the conducting channel switching from the upper film to the Si inversion layer.
    Journal of Physics D Applied Physics 01/2008; 41(4):045005. DOI:10.1088/0022-3727/41/4/045005 · 2.52 Impact Factor
  • N. Yu, L. Zhan, L. Xing, S.Y. Luo, Y.X. Xia
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we propose and demonstrate a new wavelength-switchable fiber laser with all-optical controlling. By adjusting the power of injected light in a cascaded fiber Bragg grating overlapping cavity erbium-doped fiber laser, we obtained the switching among dual wavelength, single wavelength and zero wavelength. Meanwhile, the effect of optical injection in erbium-doped fiber laser was investigated, and the optimized wavelength to control the lasing wavelength has been found. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
    Laser Physics Letters 11/2007; 5(3):206 - 209. DOI:10.1002/lapl.200710106 · 2.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present an investigation on the magnetoresistance (MR) properties and lateral photoeffect (LPE) of thin Co films deposited on Si substrates with a thin native oxide layer. A marked transition on the transport properties of our films was observed around 250 K. The thinnest Co film exhibits the largest MR of 17.5%. We explain the transport and magnetotransport properties by the conducting channel switching from the upper metallic film to the Si inversion layer. Besides the MR, a large lateral photovoltage which depends in a linear way on the incident light spot position measured on the metallic film was also investigated. The largest open-circuit position sensitivity is 27.6 mV mm−1. The LPE was discussed in terms of metal–semiconductor junction.
    Journal of Physics D Applied Physics 11/2007; 40(22):6926. DOI:10.1088/0022-3727/40/22/012 · 2.52 Impact Factor
  • S Q Xiao, H Wang, Z C Zhao, Y X Xia
    [Show abstract] [Hide abstract]
    ABSTRACT: A large lateral photoeffect (LPE) has been observed in an oxidized film Cox Mny O deposited on an n-type Si substrate by sputtering. Under the nonuniform illumination of a laser beam, the lateral photovoltage shows a high sensitivity to the spot position on the Cox MnyO surface. The largest open-circuit position sensitivity is about 34.3 mV mm−1. These phenomena were discussed in terms of the metal–semiconductor junction which exists between the oxidized film and the Si substrate. The large LPE is expected to make the oxidized film a new candidate for position-sensitive photodectors.
    Journal of Physics D Applied Physics 08/2007; 40(18):5580. DOI:10.1088/0022-3727/40/18/011 · 2.52 Impact Factor