Polarization Dependent Nonlinear Absorption in Au Nanowire Array

2014 ◽  
Vol 941-944 ◽  
pp. 483-486
Author(s):  
Ruo Chen Xing ◽  
Si Xiao ◽  
Jun He
Keyword(s):  
Nonlinear Absorption ◽  
Nanowire Array ◽  
Photon Absorption ◽  
Saturable Absorption ◽  
Linear Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Au Nanowire ◽  
Linear And Nonlinear ◽  
Au Nanowires

The polarization dependent nonlinear absorption was observed in ordered Au nanowire array. The linear and nonlinear polarized absorption at 780 nm is investigated by Z-scan. When the angle between the polarization direction of input laser and the long axis of Au nanowires is 90°(perpendicular), the linear absorption reaches the maximum and the nonlinear absorption reaches the minimum. The nonlinear absorption coefficient β decreases from positive to negative as the angle increase from 0° to 90°. There may be two nonlinear absorption mechanisms resulting in this phenomenon: two-photon absorption and saturable absorption in nanoscale.

Nonlinear Absorption and Limiting Behaviour of Monoclinic and Orthorhombic Copper Niobate

2017 ◽  
Vol 865 ◽  
pp. 20-24
Author(s):  
N. Priyadarshani ◽  
T.C. Sabari Girisun
Keyword(s):  
Nonlinear Absorption ◽  
Orthorhombic Phase ◽  
Optical Nonlinearity ◽  
Photon Absorption ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
Pore Networks ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Limiting Behaviour

Monoclinic and orthorhombic phase of copper niobate was prepared by simple solid state reaction (700°C, 900°C for 12 hours). Formation of two polymorphic phases of CuNb2O6 was ascertained by XRD and FTIR analysis. FESEM showed the presence of pore networks in both phases. Third-order optical nonlinearity and their limiting behaviour were studied by Z-scan technique using Ti: Sapphire laser (800 nm, 150 fs, 80 MHz). Both phases of copper niobate exhibit reverse saturable absorption. The observed optical limiting action was ascribed due to two-photon absorption process. Monoclinic copper niobate shows almost 100 times stronger nonlinear absorption behaviour than orthorhombic copper niobate due to peculiar distortion of NbO6 octahedra. Monoclinic copper niobate with high two photon absorption coefficient (85x10-10 m/W) and low limiting threshold (0.21 μJ/cm2) can be a better alternate for benchmark optical limiters like carbon nanotubes.

scholarly journals Nonlinear Absorption and Ultrafast Dynamics of Ag Nanoparticle

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 233
Author(s):  
Jijuan Jiang ◽  
Jun Wang ◽  
Tong Wu ◽  
Yachen Gao
Keyword(s):  
Silver Nanoparticles ◽  
Time Constant ◽  
Laser Intensity ◽  
Photon Absorption ◽  
Saturable Absorption ◽  
Phonon Coupling ◽  
Saturated Absorption ◽  
Coupling Process ◽  
Two Photon Absorption ◽  
Two Photon

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.

scholarly journals Ultrafast sub–30-fs all-optical switching based on gallium phosphide

2019 ◽  
Vol 5 (6) ◽  
pp. eaaw3262 ◽  
Author(s):  
Gustavo Grinblat ◽  
Michael P. Nielsen ◽  
Paul Dichtl ◽  
Yi Li ◽  
Rupert F. Oulton ◽  
...  
Keyword(s):  
Gallium Phosphide ◽  
Optical Switching ◽  
Near Infrared ◽  
Optical Nonlinearity ◽  
Photon Absorption ◽  
Linear Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
All Optical ◽  
All Optical Switching

Gallium phosphide (GaP) is one of the few available materials with strong optical nonlinearity and negligible losses in the visible (λ > 450 nm) and near-infrared regime. In this work, we demonstrate that a GaP film can generate sub–30-fs (full width at half maximum) transmission modulation of up to ~70% in the 600- to 1000-nm wavelength range. Nonlinear simulations using parameters measured by theZ-scan approach indicate that the transmission modulation arises from the optical Kerr effect and two-photon absorption. Because of the absence of linear absorption, no slower free-carrier contribution is detected. These findings place GaP as a promising ultrafast material for all-optical switching at modulation speeds of up to 20 THz.

scholarly journals Two-photon absorption and saturable absorption of mid-IR in graphene

2019 ◽  
Vol 114 (9) ◽  
pp. 091111 ◽  
Author(s):  
Andrew Malouf ◽  
Ori Henderson-Sapir ◽  
Sze Set ◽  
Shinji Yamashita ◽  
David J. Ottaway
Keyword(s):  
Photon Absorption ◽  
Saturable Absorption ◽  
Two Photon Absorption ◽  
Two Photon

scholarly journals Impact of the Subunit Arrangement on the Nonlinear Absorption Properties of Organometallic Complexes with Ruthenium(II) σ-Acetylide and Benzothiadiazole as Building Units §

Inorganics ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 67
Author(s):  
Eleonora Garoni ◽  
Alessia Colombo ◽  
Kenji Kamada ◽  
Claudia Dragonetti ◽  
Dominique Roberto
Keyword(s):  
Electron Acceptor ◽  
Cross Sections ◽  
Nonlinear Absorption ◽  
Organometallic Complexes ◽  
Photon Absorption ◽  
Absorption Cross ◽  
Absorption Properties ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Resonance Enhancement

In this paper, the nonlinear absorption properties of two complexes consisting of Ru(C≡CPh)(C≡C)(dppe)2 (dppe = Ph2PCH2CH2PPh2) as electron donor (D) and 4,7-di(2-thienyl)benzo[c][1,2,5]thiadiazole as electron acceptor (A) units in two different arrangement, i.e., A–D–A and D–A–D, are presented. They were measured in solution by the femtosecond open-aperture Z-scan method. The complexes show moderate two-photon absorption cross-sections σ(2) of several hundred to one thousand GM (here 1 GM = 10−50 cm4 s molecule−1 photon−1). Although they are formed by the same building units, it was found that the two-photon absorption values of the D–A–D arrangement are six times higher than that of the A–D–A one. This difference can be explained by the number of metal cores (one or two ruthenium centers), the geometrical configurations of the complexes (more or less planar), and the resonance enhancement by lowering the intermediate state.

NONLINEAR ABSORPTION AND OPTICAL LIMITING IN SOLUTIONS OF SOME RARE EARTH SUBSTITUTED PHTHALOCYANINES

2001 ◽  
Vol 10 (01) ◽  
pp. 113-121 ◽  
Author(s):  
K. P. UNNIKRISHNAN ◽  
JAYAN THOMAS ◽  
BINOY PAUL ◽  
ACHAMMA KURIAN ◽  
PRAMOD GOPINATH ◽  
...  
Keyword(s):  
Rare Earth ◽  
Absorption Coefficient ◽  
Nonlinear Absorption ◽  
Optical Limiting ◽  
Photon Absorption ◽  
Open Aperture ◽  
Pulse Excitation ◽  
Two Photon Absorption ◽  
Two Photon ◽  
532 Nm

Effective nonlinear absorption coefficient, β eff , of solutions of some rare earth substituted phthalocyanines (viz: Sm(Pc)2, Eu(Pc)2 and LaPc) was measured using open aperture Z-scan technique under nanosecond pulse excitation at 532 nm. The effect of nonlinear absorption on optical limiting in these samples was also investigated. Both nonlinear absorption and optical limiting phenomena in these samples are attributed to sequential two-photon absorption (STPA) process.

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