scholarly journals Extremely large third-order nonlinear optical effects caused by electron transport in quantum plasmonic metasurfaces with subnanometer gaps

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Takashi Takeuchi ◽  
Kazuhiro Yabana

AbstractIn this study, a third-order nonlinear optical responses in quantum plasmonic metasurfaces composed of metallic nano-objects with subnanometer gaps were investigated using time-dependent density functional theory, a fully quantum mechanical approach. At gap distances of ≥ 0.6 nm, the third-order nonlinearities monotonically increased as the gap distance decreased, owing to enhancement of the induced charge densities at the gaps between nano-objects. Particularly, when the third harmonic generation overlapped with the plasmon resonance, a large third-order nonlinearity was achieved. At smaller gap distances down to 0.1 nm, we observed the appearance of extremely large third-order nonlinearity without the assistance of the plasmon resonance. At a gap distance of 0.1 nm, the observed third-order nonlinearity was approximately three orders of magnitude larger than that seen at longer gap distances. The extremely large third-order nonlinearities were found to originate from electron transport by quantum tunneling and/or overbarrier currents through the subnanometer gaps.

2000 ◽  
Vol 637 ◽  
Author(s):  
Masanori Ando ◽  
Kohei Kadono ◽  
Kenji Kamada ◽  
Koji Ohta ◽  
Jean-François Delouis ◽  
...  

AbstractWe report on the third-order nonlinear optical responses of V2O5 films prepared by pyrolysis of spin-coated films of vanadium 2-ethylhexanoate. Temporal behavior of third-order optical nonlinearity of the spin-coated V2O5 films was examined at a wavelength of 532 nm by the degenerate four-wave mixing (DFWM) technique using a mode locked Nd/YAG laser (35 ps fwhm). Fast relaxation with a lifetime of 25 ps and slow relaxation with a lifetime of 150 ps were observed. The nonlinear transmission experiment on the spin-coated V2O5 films using the same laser source showed that the transmittance decreased with increasing intensity of the incident light. The intensity-dependent absorption coefficients (β) were roughly estimated to be 3.5×10−5 cm/W. Transient absorption properties of the V2O5 film were measured by use of the second and third harmonics of a Q switched Nd/YAG laser (10 ns fwhm). The results observed for the nonlinear transmission and the transient absorption suggest that induced absorption would contribute to the third-order optical nonlinearity of the V2O5 films with fast response times, and also suggest that the V2O5 films have potentiality for use as optical power limiting materials.


Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3194
Author(s):  
Adrian Petris ◽  
Petronela Gheorghe ◽  
Tudor Braniste ◽  
Ion Tiginyanu

The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.


2005 ◽  
Vol 52 (14) ◽  
pp. 1933-1945 ◽  
Author(s):  
I. Fuks-Janczarek ◽  
I. V. Kityk * ◽  
J. Berdowski ◽  
B. Sahraoui ◽  
C. Andraud

2017 ◽  
Vol 5 (31) ◽  
pp. 6348-6355 ◽  
Author(s):  
Yiwen Tang ◽  
Ming Kong ◽  
Xiaohe Tian ◽  
Jinghang Wang ◽  
Qingyuan Xie ◽  
...  

Two-photon (TP) microscopy has advantages for biological imaging in that it allows deeper tissue-penetration and excellent resolution compared with one-photon (OP) microscopy.


2012 ◽  
Vol 529-530 ◽  
pp. 123-128 ◽  
Author(s):  
Flora E. Imrie ◽  
Marta Corno ◽  
Piero Ugliengo ◽  
Iain R. Gibson

The properties of hydroxyapatite can be improved by substitution of biologically relevant ions, such as magnesium (Mg) and strontium (Sr), into its structure. Previous work in the literature has not reached agreement as to site preferences in these substitutions, and there are suggestions that these may change with differing levels of substitution. The current work adopted a quantum mechanical approach based on density functional theory using the CRYSTAL09 code to investigate the structural changes relating to, and site preferences of, magnesium and strontium substitution (to 10 mol%) in hydroxyapatites and also to predict the corresponding vibrational spectra in the harmonic approximation. The structures underwent full geometrical optimisation within the P63 space group, indicating an energetic site preference for the Ca (2) site in the case of Mg substitution, and the Ca (1) site in the case of Sr. Shrinkage of the unit cell was observed in the case of Mg substitution, and expansion in the case of Sr substitution, in agreement with the corresponding ionic radii. Thermodynamic properties of the structures obtained from the harmonic vibrational frequency calculations confirmed that the structures were minima on the potential energy surface. Isotopic substitutions indicated that the main contribution of Sr and Mg to vibrational modes is at frequencies < 400 cm-1.


2012 ◽  
Author(s):  
Benoı̂t Champagne ◽  
Edith Botek ◽  
Akihiro Shimizu ◽  
Takashi Kubo ◽  
Kenji Kamada ◽  
...  

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