Chapter 4 – The Intensity-Dependent Refractive Index
TL;DR: In this paper, the authors describe the optical Kerr effect, in which the refractive index of a material changes by an amount that is proportional to the square of the strength of an applied static electric field.
Abstract: Publisher Summary
The refractive index of many optical materials depends upon the intensity of the light used to measure the refractive index. The change in refractive index is sometimes called the optical Kerr effect, by analogy with the traditional Kerr electro-optic effect, in which the refractive index of a material changes by an amount that is proportional to the square of the strength of an applied static electric field. The interaction of a beam of light with a nonlinear optical medium can also be described in terms of nonlinear polarization. Another way of measuring the intensity-dependent refractive index is to use two separate beams, where the presence of the strong beam of amplitude E(ω) leads to a modification of the refractive index experienced by a weak probe wave of amplitude E(ω'). Hence, a strong wave affects the refractive index of a weak wave of the same frequency twice as much as it affects its own refractive index. This effect is known as weak-wave retardation.
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TL;DR: In this article, the authors present measurements of third order optical nonlinearities in heavy-metal oxide and sulfide glasses, using the z-scan, time-resolved zscan, and spectrally resolved two-beam coupling techniques.
Abstract: We present measurements of third order optical non-linearities in heavy-metal oxide and sulfide glasses, using the z-scan, time-resolved z-scan, and spectrally resolved two-beam coupling techniques The non-linear index of refraction is found to increase with heavy-metal and sulfide content, and the nuclear contribution to the non-linearity is found to be approximately constant at (15±3)% The largest non-resonant non-linear index of refraction occurs in 35La2S3·65Ga2S3 It is 30 times larger than the non-linear index of refraction in fused silica
53 citations
TL;DR: Because of their unique and excellent photophysical properties, lead halide perovskites are widely used in photoelectronic devices such as photodetectors, light-emitting diodes, solar cells, and la...
Abstract: Because of their unique and excellent photophysical properties, lead halide perovskites are widely used in photoelectronic devices such as photodetectors, light-emitting diodes, solar cells, and la...
50 citations
TL;DR: In this paper, the authors investigated the effect of nonlinear optical effects on femtosecond-duration laser pulses and showed that self-focusing can dramatically affect hole shape and the rate of penetration during deep hole drilling.
Abstract: Many recent investigations of micromachining with lasers, in vacuum and in ambient air environments, have demonstrated the improvements possible when using femtosecond-duration laser pulses compared with long laser pulses. There are obvious practical advantages for rapid micromachining in ambient air conditions. However, the maximum laser intensity and repetition rate are then eventually limited by the avalanche breakdown and nonlinear effects in the air through which the focused laser beam must propagate both outside the work piece and within the structure that is being machined. This paper investigates these limits in femtosecond deep hole drilling at high laser intensities in silicate glasses. In particular, it shows how nonlinear optical effects, particularly self-focusing, can dramatically affect hole shape and the rate of penetration during deep hole drilling. The experiments described here demonstrate how nonlinear Kerr focusing of femtosecond laser pulses occurs during propagation of intense femtosecond laser pulses through the atmosphere within the machined channel at powers levels significantly below the critical power for self-focusing in ambient air.
47 citations
TL;DR: In this paper, the nonlinear refraction index (n2=−(6.6±0.7)×10−11 cm2/W) and two-photon absorption (TPA) coefficients were determined for a new kind of organometallic compound [Tp*Ir(CHCHC(CH3)(NH)(C2H5))] in dilute CH2Cl2 (1× 10−3 M) solution.
43 citations
TL;DR: In this article, two plasmonic structures for bandpass and band-stop filters were proposed and numerically investigated for the bandpass filter and the bandstop filter, respectively.
Abstract: We have proposed and numerically investigated two plasmonic structures for bandpass and band-stop filters. The bandpass filter is composed of two metal–insulator–metal (MIM) waveguides coupled to each other by a nonlinear rectangular nanocavity. The band-stop filter consists of an MIM waveguide side coupled to a Kerr-type nonlinear rectangular nanocavity. The optical filtering effect is verified by two-dimensional (2-D) finite-difference time-domain (FDTD) simulations. It is demonstrated that based on optical nonlinearity we can easily make the proposed filters tunable by properly adjusting the intensity of incident light without changing the dimensions of the structures. The simulation results revealed that within the transmission spectrum, the selected central wavelength and the bandwidth of the filter can be tuned by the input signal intensity. The proposed structures are suitable to be used as highly dense integrated optical circuits, where limitations on the dimensions of the filter structure are vital.
25 citations
Cites background from "Chapter 4 – The Intensity-Dependent..."
...nonlinear behavior, which can be described as modifying the dielectric constant by the electric field.(24) The dielectric constant εd of the Kerr nonlinear material depends on the squared magnitude of the electric field, jEj2 as...
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TL;DR: In this paper, the non-linear optical polarization of an isolated atom or molecule is treated, giving careful consideration to secular and resonant terms in the perturbation expansion, and the Method of Averages introduced by Bogoliubov and Mitropolsky is used.
Abstract: The non-linear optical polarization of an isolated atom or molecule is treated, giving careful consideration to secular and resonant terms in the perturbation expansion. The Method of Averages introduced by Bogoliubov and Mitropolsky is used. The case where resonance-induced excited state populations are negligible, which is relevant to a wide range of non-linear optical experiments, is examined in detail for polarizations through third order in the perturbing fields. This yields concise expressions which are valid for any combination of applied field frequencies, including static fields.
1,184 citations
TL;DR: In this paper, the results of a series of experiments in which a giant pulsed ruby laser is used to study several different nonlinear optical effects arising from an induced optical polarization third order in the electric field strength are presented.
Abstract: This paper presents the results of a series of experiments in which a giant pulsed ruby laser is used to study several different nonlinear optical effects arising from an induced optical polarization third order in the electric field strength. The various phenomena studied are special cases of either frequency mixing or intensity-dependent changes in the complex refractive index, including Raman laser action at a focus. A wide range of crystalline and isotropic materials was studied. The theory for these effects is extended to cover resonant interactions. The experimental results are interpreted in terms of simplified models, and quantitative values for the nonlinear polarizability coefficients are given. The rather large experimental uncertainties in these coefficients are discussed.
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