Contributions of Low-Lying Excited States to Optical Nonlinearities in Squaraines

1995 ◽  
Vol 413 ◽  
Author(s):  
K. D. Singer ◽  
J. H. Andrews ◽  
J. D. V. Khaydarov ◽  
D. L. Hull ◽  
K. C. Chuang
Keyword(s):  
Dipole Moments ◽  
Harmonic Spectrum ◽  
Third Order ◽  
Linear Absorption ◽  
Third Harmonic ◽  
Squaraine Dyes ◽  
Two Photon ◽  
The Third ◽  
Squaraine Dye ◽  
Experimental Dispersion

ABSTRACTWe measured the third-harmonic spectrum for a series of both centrosymmetric and noncentrosymmetric squaraine dyes in chloroform. By fitting the experimental dispersion of the third order susceptibility, γ, to a four-level sum-over-states model, we determined the strength and location of the lowest lying two-photon-like transition. In each case, we find that the lowest two-photon-like state appears just above the dominant linear absorption peak in energy and that the transition moment to that state makes a significant contribution to the nonlinearity, as do transition moments to one or more higher-lying two-photon-like states in the ultraviolet. The spectra of one centrosymmetric dye contains an additional feature evidencing a nonzero dipole moment difference between the ground and first excited state dipole moments (δμ) that we attribute to a conformational asymmetry. A noncentrosymmetric squaraine dye shows a similar feature, which, as expected, arises from its δμ. Effects of symmetry breaking are described.

scholarly journals Selected Organometallic Compounds for Third Order Nonlinear Optical Application

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 254 ◽  
Author(s):  
Anna Popczyk ◽  
Aouatif Aamoum ◽  
Anna Migalska-Zalas ◽  
Przemyslaw Płóciennik ◽  
Anna Zawadzka ◽  
...  
Keyword(s):  
Physical Vapor Deposition ◽  
Incident Beam ◽  
Organometallic Compounds ◽  
Basis Set ◽  
Nonlinear Susceptibility ◽  
Third Order ◽  
Linear Absorption ◽  
Third Harmonic ◽  
The Third ◽  
Linear Optical Properties

In this paper, we present the third harmonic generation response of Znq2 (Bis-(8-hydroxyquinolinato)zinc), Cuq2 (8-Hydroxyquinoline copper(II)), and Alq3 (Tris-(8-hydroxyquinoline)aluminum) organometallic compounds. An experiment was conducted for s and p polarizations of incident beam, using the Maker fringes technique. The third order nonlinear susceptibility χ(3) was estimated using the Kubodera and Kobayashi comparative model, on the grounds that presented compounds exhibit high linear absorption of the generated third harmonic wavelength (355 nm). These complexes were deposited as thin films using the physical vapor deposition (PVD) method. Investigated complexes vary in terms of the coordination center and number of quinoline ligands, which visibly influence their nonlinear response. The global hybrid B3LYP functional with the basis set 6-31G(d) was used in computing the linear and non-linear optical properties. The computed γtot value (8765.36 × 10−36 esu for Cuq2) is superior to that of methylene blue (γ = 32.00 × 10−36 esu). The calculated theoretical values were found to be in good agreement with the experimental results.

scholarly journals Giant Third-Order Nonlinear Response of Mixed Perovskite Nanocrystals

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 389
Author(s):  
Aya M. Abu Baker ◽  
Ganjaboy S. Boltaev ◽  
Mazhar Iqbal ◽  
Mikhail Pylnev ◽  
Nasser M. Hamdan ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Laser Pulses ◽  
Photon Absorption ◽  
Third Order ◽  
Central Wavelength ◽  
Third Harmonic ◽  
Perovskite Nanocrystals ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Third

Mixed (FAPbI3)0.92(MAPbBr3)0.08 perovskite thin films exhibit strong nonlinear optical responses, rendering them promising candidates for applications in photonics and optical communications. In this work, we present a systematic study on the ultrafast third-order nonlinear optical processes in mixed perovskite nanocrystals (NCs) by exploring the generation of third harmonic radiation and giant two-photon absorption-based photoluminescence (PL) when excited by femtosecond laser pulses of a 1030 nm central wavelength. A comparative analysis of the coherent third harmonic generation in the thin-film-containing perovskite nanocrystals has shown a 40× enhancement of the third harmonic signal compared to the signal generated in the pure quartz substrate. The cubic dependence of the third-nonlinear optical response of the (FAPbI3)0.92(MAPbBr3)0.08 perovskites on the intensity of the driving radiation was identified using broadband 38 femtosecond driving pulses. The positive nonlinear refractive index (γ = +1.4 × 10−12 cm2·W−1) is found to play an important role in improving the phase-matching conditions of the interacting pulses by generating a strong third order harmonic. The giant two-photon absorption (TPA)-assisted PL peak was monitored and a blue shift of the PL was obtained in the higher intensity range of the laser pulses, with the absorption coefficient β estimated to be~+7.0 cm·MW−1 at a 1030 nm laser wavelength.

scholarly journals Ultrafast Third-Order Nonlinear Optical Response Excited by fs Laser Pulses at 1550 nm in GaN Crystals

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3194
Author(s):  
Adrian Petris ◽  
Petronela Gheorghe ◽  
Tudor Braniste ◽  
Ion Tiginyanu
Keyword(s):  
Harmonic Generation ◽  
Nonlinear Optical ◽  
Laser Pulses ◽  
Third Harmonic Generation ◽  
High Repetition Rate ◽  
Third Order ◽  
Third Harmonic ◽  
The Third ◽  
High Repetition ◽  
Gan Crystal

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.

Contribution of the 2 ^1Ag state to the third-order optical nonlinearity in a squaraine dye: errata

1994 ◽  
Vol 19 (22) ◽  
pp. 1909 ◽  
Author(s):  
James H. Andrews ◽  
John D. V. Khaydarov ◽  
Kenneth D. Singer
Keyword(s):  
Optical Nonlinearity ◽  
Third Order ◽  
The Third ◽  
Squaraine Dye

Experimental dispersion of the third order optical susceptibility of Ag nanoparticles

2012 ◽  
Vol 29 (9) ◽  
pp. 2410 ◽  
Author(s):  
Rodrigo Sato ◽  
Hiroyoshi Momida ◽  
Masato Ohnuma ◽  
Masato Sasase ◽  
Takahisa Ohno ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Third Order ◽  
The Third ◽  
Optical Susceptibility ◽  
Experimental Dispersion

scholarly journals Experimental dispersion of the third-order optical susceptibility of graphene oxide

2020 ◽  
Vol 10 (12) ◽  
pp. 3041
Author(s):  
Luhao Kang ◽  
Rodrigo Sato ◽  
Boyi Zhang ◽  
Yoshihiko Takeda ◽  
Jie Tang
Keyword(s):  
Graphene Oxide ◽  
Third Order ◽  
The Third ◽  
Optical Susceptibility ◽  
Experimental Dispersion

scholarly journals Photolysis of SiH4 by the Third Harmonic of a Nd:YAG Laser at 355 NM

1996 ◽  
Vol 16 (4) ◽  
pp. 245-253
Author(s):  
K. Sentrayan ◽  
E. Haque ◽  
A. Michael ◽  
V. S. Kushawaha
Keyword(s):  
Laser Energy ◽  
Emission Spectra ◽  
Photon Absorption ◽  
Absorption Process ◽  
Third Harmonic ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Third ◽  
Atomic Lines ◽  
White Deposit

The photolysis of silane (SiH4) was carried out using the third harmonic of a Nd: YAG laser at 355 nm, at a fixed SiH4 pressure of 350 Torr, varying the laser energy fluence in the range of 30–300 Jcm-2. The emission spectra indicates that the photofragments formed are SiH2, SiH, Si, H2, and H. The (A1B1-X1A1) transitions at 552.7 nm, 525.3 nm, 505.6 nm, and 484.7 nm of SiH2 are due to a two photon absorption process. The (A2Δ-X2π) transitions of SiH at 425.9 nm, 418 nm, 414.2 nm, 412.8 nm and 395.6 nm are due to a three photon absorption process. The brownish white deposit on the cell windows indicates the presence of amorphous silicon (a:Si-H). The two atomic lines of Si(4s1P0→ 3p21D2) at 288.1 nm, and (4s3Pj→ 3P3Pj) at 251.6 nm are observed. The atomic Si transitions are due to a three photon absorption. We observed seven transitions due to molecular hydrogen at wavelengths 577.5 nm, 565.5 nm, 534.4 nm, 542.5 nm, 471 nm, 461.7 nm, and 455.4 nm. These bands are due to a four photon absorption proc6ss. In addition to the molecular bands we also observed hydrogen atomic lines Hβ, Hγ and Hδ.

Nonlinear Optics of Linear Conjugated Polymers

1992 ◽  
Vol 247 ◽  
Author(s):  
D. Guo ◽  
S. Mazumdar ◽  
G. I. Stegeman ◽  
M. Cha ◽  
D. Neher ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Dipole Moments ◽  
Harmonic Signal ◽  
Oscillator Strengths ◽  
Experimental Investigations ◽  
Transition Dipole ◽  
Third Harmonic ◽  
The Third ◽  
Transition Dipole Moments ◽  
Spectral Ranges

The third order nonlinear optical properties of conjugated polymers have been considered promising since the 1970s when Sauteret et al reported large non-resonant values in PTS.[1] Although it is well-understood that the physical origin of the nonlinearities is due to the delocalization of the π-electrons, the details, and how best to calculate them have been the focus of a continuing theoretical dialogue. Until recently, experimental investigations of nonlinearities have been limited to only a few wavelengths. Now third harmonic generation (THG), which accesses only the electronic nonlinearities, can be performed over wide spectral ranges, for example from 500 to 2000 nm. The resulting third harmonic wavelength typically spans the electronic molecular transitions associated with the nonlinearities. By measuring the spectral distribution of both the amplitude and phase of the third harmonic signal, the dominant transitions (between the“essential states”) contributing to the nonlinearity can be identified. Such information is most useful for comparing with theories in which the oscillator strengths (transition dipole moments) for the various molecular transitions are calculated.

GIANT THIRD-ORDER KERR NONLINEARITIES AND SLOW OPTICAL SOLITONS IN DOUBLE QUANTUM-WELL

2010 ◽  
Vol 24 (17) ◽  
pp. 1899-1905
Author(s):  
XUN XIAO
Keyword(s):  
Quantum Wells ◽  
Probe Pulse ◽  
Optical Solitons ◽  
Double Quantum ◽  
Third Order ◽  
Raman Resonance ◽  
Linear Absorption ◽  
Two Photon ◽  
Double Quantum Well ◽  
Slow Group

We show the formation of slow optical solitons in the asymmetric coupled double quantum wells (CQW) via a two-photon Raman resonance. With the consideration of real parameters in AlGaAs -based CQW, we indicate the possibility to have cancelation of the linear absorption, giant Kerr nonlinearities, and slow group velocity propagation of the weak probe pulse at the same one-photon detuning frequency around several THz .

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