The Experts below are selected from a list of 36363 Experts worldwide ranked by ideXlab platform
Jun Wang - One of the best experts on this subject based on the ideXlab platform.
-
Nonlinear Absorption and Ultrafast Dynamics of Ag Nanoparticle
'MDPI AG', 2021Co-Authors: Jijuan Jiang, Jun Wang, Yachen GaoAbstract:Resonant Nonlinear optical Absorption of silver nanoparticles was studied experimentally via open aperture Z-scan using 130 fs, 400 nm laser pulses. Experimental results show that, at low laser intensity, silver nanoparticles can exhibit saturated Absorption. While at high laser intensity, it shows reverse saturated Absorption. The saturable Absorption is explained in terms of ground state plasmon bleaching, while the reverse saturable Absorption is believed to be from two-photon Absorption. Saturable optical intensity and two-photon Absorption coefficient were obtained to be 1.3×1010 W/m2 and 3.3×10−10 m/W, respectively. The energy relaxation process of Ag nanoparticles after laser excitation was studied via pump-probe technique at 400 nm. Experimental results demonstrated that energy relaxation included electron-phonon coupling process with time constant τ1=(713±50) fs, and phonon-phonon coupling process with time constant τ2=(25.2±3) ps, respectively
-
ultrafast Nonlinear optical response of molybdenum nano film in wide wavelength range
Optical Materials, 2019Co-Authors: Zhipeng Huang, Jun Wang, Long Zhang, Yafeng Xie, Xin Chen, Chi ZhangAbstract:Abstract Nonlinear optical responses in molybdenum (Mo) nano-film with different thicknesses (15 nm, 25 nm, 50 nm and 70 nm) are investigated by using 515 and 1030 nm fs laser pulses. The investigation shows that Mo nano-film has prominent reverse saturable Absorption in both wavelengths. The Nonlinear Absorption capability is thickness-dependent. The effective Nonlinear Absorption coefficients of samples are on the order of 103–104 cm GM−1 in both 1030 nm and 515 nm, much larger than typical semiconductors. The origin of wide wavelength range Nonlinear optical Absorption can be attributed to free carries Absorption.
-
plasmonic nanoparticles embedded in single crystals synthesized by gold ion implantation for enhanced optical Nonlinearity and efficient q switched lasing
Nanoscale, 2018Co-Authors: Weijie Nie, Jun Wang, Ningning Dong, Yuxia Zhang, Rene Hubner, Roman Bottger, Shengqiang Zhou, Hiroshi Amekura, Feng ChenAbstract:We report on the synthesis of embedded gold (Au) nanoparticles (NPs) in Nd:YAG single crystals using ion implantation and subsequent thermal annealing. Both linear and Nonlinear Absorption of the Nd:YAG crystals have been enhanced significantly due to the embedded Au NPs, which is induced by the surface plasmon resonance (SPR) effect in the visible light wavelength band. Particularly, through a typical Z-scan system excited by a femtosecond laser at 515 nm within the SPR band, the Nonlinear Absorption coefficients of crystals with Au NPs have been observed to be nearly 5 orders of magnitude larger than that without Au NPs. This giant enhancement of Nonlinear Absorption properties is correlated with the saturable Absorption (SA) effect, which is the basis of passive Q-switching or mode-locking for pulsed laser generation. In addition, the linear and Nonlinear Absorption enhancement could be tailored by varying the fluence of implanted Au+ ions, corresponding to the NP size and concentration modulation. Finally, the Nd:YAG wafer with embedded Au NPs has been applied as a saturable absorber in a Pr:LuLiF4 crystal laser cavity, and efficient pulsed laser generation at 639 nm has been realized, which presents superior performance to the MoS2 saturable absorber based system. This work opens an avenue to enhance and modulate the Nonlinearities of dielectrics by embedding plasmonic Au NPs for efficient pulsed laser operation.
-
Nonlinear Absorption induced transparency and optical limiting of black phosphorus nanosheets
ACS Photonics, 2017Co-Authors: Jiawei Huang, Saifeng Zhang, Ningning Dong, Wanhong Zhang, Jun WangAbstract:This work reports the wavelength- and pulse-duration-dependent Nonlinear optical properties of exfoliated black phosphorus (BP). We found that BP nanosheets exhibit better saturable Absorption response in the visible range than that in the near-infrared range and better response under 6 ns pulse excitation than that under 340 fs excitation. In addition, we propose that the optically induced transparency and optical limiting properties of BP dispersions mainly originate from the competition between saturable Absorption and Nonlinear scattering.
-
tin diselenide as a new saturable absorber for generation of laser pulses at 1μm
Optics Express, 2017Co-Authors: Chen Cheng, Jun Wang, Ningning Dong, Feng ChenAbstract:The Nonlinear optical responses of two-dimensional (2D) few-layer tin diselenide (SnSe2) have been investigated in this work. By applying the Z-scan technique, the saturable Absorption of SnSe2 thin film has been observed at a wavelength of ~1μm, which enables SnSe2, a new saturable absorber for pulsed laser generation. A detailed exploration of the Nonlinear Absorption of SnSe2 film and their dependence on excitation pulse energy is carried out. Our results show that saturation intensity of the Nonlinear Absorption is ~23.78 GW/cm2 and corresponding Nonlinear Absorption coefficients are at a range from −13596 to −2967.3 cm/GW. By employing the SnSe2-coated mirror as a saturable absorber, the passively Q-switched lasing has been achieved on a crystalline waveguide platform at ~1 μm.
J R Sambles - One of the best experts on this subject based on the ideXlab platform.
-
Nonlinear Absorption of a carbocyanine dye 1 1 3 3 3 3 hexamethylindotricarbocyanine iodide using a z scan technique
Applied Physics Letters, 1995Co-Authors: Stewart Swatton, Kevin Welford, S J Till, J R SamblesAbstract:Experimental and theoretical data are presented for the Nonlinear Absorption of the organic laser dye 1,1’,3,3,3’,3’‐hexamethylindotricarbocyanine iodide (HITCI) using a z‐scan technique. Experimental data show an induced Absorption above laser fluences of 10 mJ/cm2 and a saturation of the Nonlinear Absorption above fluences of 0.5 J/cm2. A self‐consistent theoretical analysis, based on rate equations, is used to predict accurately the results of z scans taken at different pulse energies. Photophysical parameters, including the excited state lifetimes and Absorption cross sections are derived for HITCI.
Long Zhang - One of the best experts on this subject based on the ideXlab platform.
-
ultrafast Nonlinear optical response of molybdenum nano film in wide wavelength range
Optical Materials, 2019Co-Authors: Zhipeng Huang, Jun Wang, Long Zhang, Yafeng Xie, Xin Chen, Chi ZhangAbstract:Abstract Nonlinear optical responses in molybdenum (Mo) nano-film with different thicknesses (15 nm, 25 nm, 50 nm and 70 nm) are investigated by using 515 and 1030 nm fs laser pulses. The investigation shows that Mo nano-film has prominent reverse saturable Absorption in both wavelengths. The Nonlinear Absorption capability is thickness-dependent. The effective Nonlinear Absorption coefficients of samples are on the order of 103–104 cm GM−1 in both 1030 nm and 515 nm, much larger than typical semiconductors. The origin of wide wavelength range Nonlinear optical Absorption can be attributed to free carries Absorption.
-
dispersion of Nonlinear refractive index in layered ws 2 and wse 2 semiconductor films induced by two photon Absorption
Optics Letters, 2016Co-Authors: Ningning Dong, Saifeng Zhang, Long Zhang, Niall Mcevoy, Xiaoyan Zhang, Yun Cui, Georg S Duesberg, Jun WangAbstract:Both the Nonlinear Absorption and Nonlinear refraction properties of WS2 and WSe2 semiconductor films have been characterized by using Z-scan technique with femtosecond pulses at the wavelength of 1040 nm. It is found that these films have two-photon Absorption response with the Nonlinear Absorption coefficient of ∼103 cm GW−1, and a dispersion of Nonlinear refractive index in the WS2 films that translated from positive in the monolayer to negative in bulk materials.
-
broadband ultrafast Nonlinear Absorption and Nonlinear refraction of layered molybdenum dichalcogenide semiconductors
Nanoscale, 2014Co-Authors: Kangpeng Wang, Yanyan Feng, Chunxia Chang, Jingxin Zhan, Chengwei Wang, Quanzhong Zhao, Jonathan N Coleman, Long Zhang, Werner J BlauAbstract:A series of layered molybdenum dichalcogenides, i.e., MoX2 (X = S, Se and Te), were prepared in cyclohexyl pyrrolidinone by a liquid-phase exfoliation technique. The high quality of the two-dimensional nanostructures was verified by transmission electron microscopy and Absorption spectroscopy. Open- and closed-aperture Z-scans were employed to study the Nonlinear Absorption and Nonlinear refraction of the MoX2 dispersions, respectively. All the three-layered nanostructures exhibit prominent ultrafast saturable Absorption (SA) for both femtosecond (fs) and picosecond (ps) laser pulses over a broad wavelength range from the visible to the near infrared. While the dispersions treated with low-speed centrifugation (1500 rpm) have an SA response, and the MoS2 and MoSe2 dispersions after higher speed centrifugation (10 000 rpm) possess two-photon Absorption for fs pulses at 1030 nm, which is due to the significant reduction of the average thickness of the nanosheets; hence, the broadening of band gap. In addition, all dispersions show obvious Nonlinear self-defocusing for ps pulses at both 1064 nm and 532 nm, resulting from the thermally-induced Nonlinear refractive index. The versatile ultrafast Nonlinear properties imply a huge potential of the layered MoX2 semiconductors in the development of nanophotonic devices, such as mode-lockers, optical limiters, optical switches, etc.
R A Ganeev - One of the best experts on this subject based on the ideXlab platform.
-
influence of pvp polymer concentration on Nonlinear Absorption in silver nanoparticles at resonant excitation
Applied Physics A, 2020Co-Authors: Sandeep Kumar Maurya, R A Ganeev, Anuradha RoutAbstract:Silver nanoparticles exhibit saturable Absorption at resonant excitation, which upon addition of the polymer as a capping agent, exhibit reverse saturable Absorption. These Nonlinear optical processes play an important role in the overall Nonlinear optical properties of silver nanoparticle. Thus, with this viewpoint, the Nonlinear Absorption of silver nanoparticles in deionized water in the presence of varying concentration polyvinylpyrrolidone polymer was investigated using femtosecond laser pulses at 400 nm. This study shows that the saturable Absorption process is significantly suppressed at high concentration of the polymer. The silver nanoparticle with smaller size shows pure reverse saturable Absorption process with the respective coefficient of $$\beta =7.55\times {10}^{-12}\, \mathrm{c}\mathrm{m}/\mathrm{W}$$. The change in the Nonlinear optical response from combined saturable Absorption and reverse saturable Absorption to pure reverse saturable Absorption process was observed as the concentration of polymer increases.
-
ag 2 s quantum dots in the fields of picosecond and femtosecond uv and ir pulses optical limiting Nonlinear Absorption and refraction properties
Applied Physics B, 2019Co-Authors: Yue Fu, R A Ganeev, Chen Zhao, Sandeep Kumar Maurya, Weili Yu, Ke ZhangAbstract:We demonstrate strong optical Nonlinearities of silver sulfide (Ag2S) quantum dots (QDs) in the ultraviolet range. The 4-nm Ag2S QDs were prepared by chemical method and analyzed using picosecond (800 nm and 400 nm, 200 ps) and femtosecond (800 nm and 400 nm, 60 fs) laser pulses. Our Z-scan measurements show that these QDs have large Nonlinear Absorption coefficient (~ 10−3 cm W−1) at 400 nm. We also demonstrate the transient Absorption and optical limiting in Ag2S QDs. Variations of the signs of Nonlinear refractive indices and Nonlinear Absorption coefficients of QDs are demonstrated by changing pulse width and wavelength of probe radiation.
-
optical limiting Nonlinear refraction and Nonlinear Absorption of the associates of cd 0 5 zn 0 5 s quantum dots and dyes
Optics Express, 2018Co-Authors: Ganjaboy S Boltaev, A. I. Zvyagin, M. S. Smirnov, O. V. Ovchinnikov, B R Sobirov, R A GaneevAbstract:The optical limiting properties of alloyed Cd0.5Zn0.5S quantum dots associated with erythrosine dye are analyzed using 532 nm, 40 ps pulses. We show that joint influence of saturable Absorption, reverse saturable Absorption and two-photon Absorption cause the optical limiting of 532 nm radiation at the pulse energies exceeding 1 mJ. The Nonlinear refraction and Nonlinear Absorption of these quantum dots associated with different organic dyes were studied using 1064 nm and 532 nm radiation. The Nonlinear refraction index and Nonlinear Absorption coefficient of Cd0.5Zn0.5S quantum dots were measured at λ = 1064 nm to be 2 × 10-13 cm2 W-1 and 1.2 × 10-8 cm W-1, while the reverse saturable Absorption of Cd0.5Zn0.5S quantum dots and erythrosine at λ = 532 nm was almost two orders larger. The potential applications of these quantum dots for high-order harmonic generation are discussed.
-
Nonlinear Absorption of some thiazine xanthene and carbocyanine dyes
Optik, 2018Co-Authors: R A Ganeev, A. I. Zvyagin, M. S. Smirnov, Ganjaboy S Boltaev, O. V. OvchinnikovAbstract:Abstract The saturated and two-photon Absorption of various classes of heterocyclic dyes [thiazine (thionine), xanthene (erythrosine), and carbocyanine (3,3′-di-(γ-sulfopropyl)-4,4′,5,5′-dibenzo-9-ethylthiacarbocyaninebetaine pyridinium salt, DEC)] possessing optical Absorption in the 500–680 nm range were measured at the wavelengths of 1064 and 532 nm using nanosecond (10 ns) and picosecond (40 ps) pulses and z-scan technique. It was shown that reverse saturated Absorption unlikely plays important role in those dyes. We defined the two-photon Absorption coefficients of thionine and erythrosine at 1064 nm using 40 ps pulses (0.8 × 10−11 and 1.0 × 10−11 cm W−1 respectively). The concurrence of saturated Absorption and two-photon Absorption was analyzed in the case of thionine and erythrosine using various models. It was suggested that dimerization of those dyes significantly suppresses the Nonlinear optical response in the case of both 10 ns and 40 ps pulses of 532 nm radiation. At the same time it was found that, in the case of 532 nm pulses, the monomers of thionine participate in the processes of saturated Absorption and two-photon Absorption, while J-aggregates of DEC show predominantly two-photon Absorption.
-
Nonlinear optical Absorption and refraction in ru pd and au nanoparticle suspensions
Applied Physics B, 2010Co-Authors: R A Ganeev, Ganjaboy S Boltaev, R I Tugushev, T UsmanovAbstract:We present the results of studies of the Nonlinear optical properties of Pd, Ru, and Au nanoparticles. We studied the Nonlinear refraction and Nonlinear Absorption of suspensions of these nanoparticles at 1064-nm wavelength. A relatively strong Nonlinear Absorption of the Pd nanoparticles was observed in the case of 1064-nm, 50-ps pulses (β=2×10−9 m W−1). The Ru and Pd nanoparticles showed weak negative Nonlinear refraction (γ∼−(6–8)×10−16 m2 W−1) in this spectral range. In the case of the Au nanoparticles, a saturated Absorption at 532 nm dominated over other Nonlinear optical processes.
Ayhan Elmali - One of the best experts on this subject based on the ideXlab platform.
-
influence of boron concentration on Nonlinear Absorption and ultrafast dynamics in gase crystals
Optical Materials, 2016Co-Authors: Ahmet Karatay, Mustafa Yuksek, Huseyin Ertap, Ali Kemal Mak, Mevlut Karabulut, Ayhan ElmaliAbstract:Abstract The Nonlinear Absorption properties and ultrafast dynamics of pure and boron doped GaSe crystals have been studied by open aperture Z-scan and ultrafast pump probe spectroscopy techniques. All of the studied crystals showed Nonlinear Absorption under 100 fs pulse duration and 1200 nm wavelength excitations. Nonlinear Absorption coefficients increase with increasing the doping ratio of boron atoms in crystals. These findings indicate that free carrier density increase with boron doping and this behavior leads to excited state Absorption. Second harmonic generation signals of crystals were detected with the help of fiber optic spectrometer. The blue shift in the energy of the second harmonic generation signals was observed in boron doped crystals. Ultrafast pump probe experiments indicate that the excited state Absorption signal with long lifetime observed for undoped GaSe crystal switches to bleach signal for boron doped GaSe crystals at 625 nm probe wavelength. The effects of increasing doping ratio were observed on ultrafast dynamics as a switching time changes. Our experimental results indicate that it is possible to control Nonlinear Absorption properties, frequency conversion and ultrafast dynamics of GaSe crystal by changing boron doping ratio.
-
synthesis characterization and Nonlinear Absorption of novel octakis poss substituted metallophthalocyanines and strong optical limiting property of cupc
Dalton Transactions, 2008Co-Authors: Tanju Ceyhan, Ayhan Elmali, Mustafa Yuksek, Gul H Yaglioglu, Bekir Salih, Mehmet K Erbil, Ozer BekarogluAbstract:In this study, the preparation of some novel metallophthalocyanine (MPcs) complexes substituted with octakis(mercaptopropylisobutyl-POSS) functional group was achieved. By the reaction of [1-(3-mercapto)propyl-3,5,7,9,11,13,15-isobutylpentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane 1 with 4,5-dichloro-1,2-dicyanobenzene 2 in THF as the solvent in the presence of K2CO3 as the base, the phthalonitrile derivative 3 was synthesized. Compound 3 reacted with CoCl2·6H2O in ethylene glycol to furnish a novel cobalt(II) phthalocyanine 4. The tetramerization of 3 with urea and CuCl in the absence of solvent gave the novel Cu(II) phthalocyanine 5; while with Zn(OAc)2·2H2O in dry DMF gave the novel zinc(II) phthalocyanine 6. The structures of the target compounds were confirmed by elemental analysis, UV/VIS, IR, MALDI-TOF MS and 1H NMR spectra. Nonlinear Absorptions of MPcs 4–6 in chloroform solution were investigated by using Z-scan measurement technique with 4 ns pulses at 532 nm wavelength. While CuPc 5 showed very high Nonlinear Absorption, MPcs 4 and 6 did not show considerable Nonlinear Absorption. Investigations of optical limiting properties of 5 revealed that this material is a very good candidate for optical limiting applications.
