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Ultrafast spectroscopy of semiconductor saturable absorber mirror

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Chinese Optics Letters 2010年第7期8卷 676-679页

作者：张靓 Dominik Bauer Farina Knig Thomas Dekorsy 张喜和陈亚符 Department of Physics Changchun University of Science and Technology Department of Physics and Center of Applied photonics University of Konstanz

Ultrafast spectroscopy of semiconductor saturable absorber mirror （SESAM） is measured using a femtosec- ond pump-probe experiment. This allows dynamic responses of SESAM in the cavity to be concluded by ultrafast spectroscopy. Change in reflection is measured as a function of pump-probe delay for different pump excitation fluences. Change of nonlinear reflection of SESAM is measured as a function of incident light energy density. When the excitation fluence increases, nonlinear change in ultrafast spectroscopy of SESAM becomes increasingly significant. When SESAM is pumped by an ultrahigh excitation fluence, the energy density of which is approximately 1400 μJ/cm2, two-photon absorption can be observed visibly in its ultrafast spectroscopy.

关键词： Dynamic response Light reflection Mirrors Probes Pumps two photon processes

Exclusive γ^(*)γ processes

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Chinese Physics C 2010年第6期34卷 822-830页

作者： V.L.Chernyak Budker Institute of Nuclear Physics

A short review of experimental and theoretical results on the large angle cross sections ＂γγ→ twomesons＂ and the form factors γ＊γ→ P = {π, η, η＇} is given.

关键词： mesons two photon processes form factor

Performance analysis of the silicon waveguide-based wavelength converter

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Optoelectronics Letters 2011年第2期7卷 96-100页

作者：王莹桑新柱尹霄丽苑金辉 Ashiq Hussaun 余重秀忻向军 Key Laboratory of Information photonics and Optical Communications Ministry of Education Beijing University of Posts and Telecommunications

The conversion efficiency and noise figure (NF) of the silicon-on-insulator (SOI) waveguide-based wavelength converter are investigated with the coupled equations. The effects of the pump power, the nonlinear absorption and the waveguide length on the conversion efficiency and noise figure are discussed. The conversion efficiency decreases with the increasing pump power and the noise figure is degraded due to the two-photon absorption (TPA) and the TPA-induced free-carrier absorption (FCA) at the higher pump power. With the increasing of the free carrier lifetime, the conversion efficiency will decrease and the noise figure will increase accordingly. The optimal waveguide length depends on the pump power and the free carrier lifetime. In practical applications, the high conversion efficiency and low noise figure can be achieved by choosing suitable parameters of the silicon waveguide.

关键词： Absorption Carrier lifetime Conversion efficiency Noise figure Pumps two photon processes

Nd^(3+) doped fluorochlorozirconate glass: 3.9 μm MIR emission properties and energy transfer

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Optoelectronics Letters 2017年第5期13卷 344-348页

作者：晏明张晓松李岚莫兆军金含丁琪丁文龙 Key Laboratory for Optoelectronic Materials and Devices of Tianjin Key Laboratory of Display Materials and Photoelectric Devices of Ministry of Education Institute of Material Physics Tianjin University of Technology

The Nd^(3+) doped fluorochlorozirconate(FCZ) glass was prepared by melt-quenching method. The 3.9 μm emission from Nd^(3+) ions is attributed to the two-photon absorption process. The strong emission transition at 3.9 μm fluorescence peak intensity, corresponding to the ~4G_(11/2)→~2K_(13/2) transition, is directly proportional to the NaCl concentration. With the increase of the Cl-ions amount, the mid-infrared(MIR) luminescent intensity is significantly enhanced. Additionally, the Judd-Ofelt(J-O) parameter ?_2 is larger than that of the fluorozirconate(FZ) glass, which indicates the covalency of the bond between RE ions and ligand is stronger as Cl-ions substitution of F-ions in chloride FZ glass. The X-ray diffraction(XRD) patterns show that the amorphous glassy state keeps the FZ glass network structure. In brief, the advantageous spectroscopic characteristics make the Nd^(3+)-doped FCZ glass be a promising candidate for application of 3.9 μm emission.

关键词： Energy transfer Ions two photon processes X ray diffraction

two-photon absorption of monolayer graphene suspensions in femtosecond regime

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Chinese Optics Letters 2012年第7期10卷 80-82页

作者：樊洋蒋治国姚陆锋 College of Sciences Naval University of Engineering

Nonlinear absorption of monolayer graphene suspension is studied in the wavelength of 800 nm using Z-scan method with 50-fs pulses. Nonlinear absorption property of graphene suspension at different excitation intensit... 详细信息

关键词： Monolayers two photon processes

Coherent control of two-photon absorption of Pr^(3+) ion by shaped ultrashort laser pulses

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Chinese Optics Letters 2013年第4期11卷 73-76页

作者：程文静张诗按贾天卿马婧冯东海孙真荣 State Key Laboratory of Precision Spectroscopy Department of Physics East China Normal University

Enhancing the photoluminescence and depressing the background emission are important problems in rare earth ion-doped materials. In this letter, the two-photon absorption （TPA） probability in a Pr3＋ ion system is enhanced by a factor of 12.3 by a π-phase step scanning of ultrashort laser pulses. This level is significantly higher than that achieved by a transform-limit pulse. However, the laser intensity of shaped pulse is reduced to 37% of the initial transform-limited pulse. In this method, the TPA probability can also be reduced to 58%. Furthermore, the el＇feet of the shift of the intermediate energy level and the bandwidth of final states on TPA probability is discussed.

关键词： Light absorption Luminescence of organic solids Metal ions Probability two photon processes

Nonlinear two-photon absorption properties induced by femtosecond laser with the films of two novel anthracene derivatives

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Chinese Optics Letters 2012年第10期10卷 49-52页

作者：李亮吴谊群王阳 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Key Lab of Functional Inorganic Material Chemistry(Heilongjiang University) Ministry of Education

two novel anthracene derivatives containing 4-vinylpyridine （FPEA） and 2-vinylpyridine （TPEA） poly（methyl methacrylate） films are prepared on quartz glass substrates. Their nonlinear absorption properties are investigated by using a 120-fs, 800-nm Ti：sapphire femtosecond pulsed laser operating at a 1-kHz repetition rate. The unique nonlinear absorption properties of these new compounds are observed by utilizing a Z-scan system. These two-photon absorption （TPA） properties are proven by the two-photon fluorescence excited at 800 nm. The FPEA and TPEA films have nonlinear TPA coefficients of 0.164 and 0.148 cm/GW and the TPA cross sections of 3.345 × 10^-48 and 3.081 × 10^-48 cm4 ·s/photon, respectively. The influence of the chemical structures on the nonlinear TPA properties of the compounds is also discussed. The highly nonlinear TPA activities of the films implied that the new anthracene derivatives are suitable materials with promising applications in super-high-density three-dimensional data storage and nano- or microstructure fabrication.

关键词： Anthracene Esters Lasers Light absorption Luminescence of organic solids Quartz Sapphire Substrates two photon processes

Investigation of transient two-photon excited fluorescence in biological tissue

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Chinese Optics Letters 2012年第5期10卷 44-46页

作者：邱怡申陈恩果李高明李晖 Key Laboratory of OptoElectronic Science and Technology for Medicine Ministry of Education Fujian Provincial Key Laboratory for Photonics TechnologyFujian Normal University Department of Optical Engineering Zhejiang University

The fluorescence power from biological tissue excited by a femtosecond laser pulse compared with excitation power does not appear to obey a simple quadratic relationship given by the steady non-linear theory. A more reliable analysis is developed based on transient two-photon absorption because the response time of two-photon absorption is longer than the width of a femtosecond pulse. Good agreement is obtained between the theoretical analysis and the experimental results of fluorescence power versus excitation power. This letter offers potential value to non-linear optics in biological tissues.

关键词： Electromagnetic pulse Fluorescence Light absorption Luminescence of organic solids two photon processes Ultrafast lasers Ultrashort pulses

Repetition rate dependence of absorption of fused silica irradiated at 193 nm

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Chinese Optics Letters 2013年第5期11卷 69-71页

作者：刘卫静李斌成 Institute of Optics and Electronics Chinese Academy of Sciences University of Chinese Academy of Sciences

Repetition rate-dependent absorbance measurements of synthetic fused silica at 193-nm irradiation are performed in tile range of 50-1000 Hz with an ArF laser calorimeter. The ＂apparent＂ single- and two- photon absorption coefficients are determined by measuring the laser fiuence-dependent absorbance of fused silica samples with different thicknesses to separate the surface absorption and bulk absorption. The measurement results indicate a reversible nonlinear increase of both apparent single- and two-photon absorption coefficients with increasing repetition rate for the synthetic fused silica, whereas the surface absorption shows no dependence on the repetition rate.

关键词： two photon processes