Shear waves in a resonator with cubic nonlinearity

Shear waves with finite amplitude in a one-dimensional resonator in the form of a layer of a rubber-like medium with a rigid plate of finite mass at the upper surface of the layer are investigated. The lower boundary of the layer oscillates according to a harmonic law with a preset acceleration. The equation of motion for particles in a resonator is determined using a model of a medium with a single relaxation time and cubical dependence of the shear modulus on deformation. The amplitude and form of shear waves in a resonator are calculated numerically by the finite difference method at shifted grids. Resonance curves are obtained at different acceleration amplitudes at the lower boundary of a layer. It is demonstrated that, as the oscillation amplitude in the resonator grows, the value of the resonance frequency increases and the shape of the resonance curve becomes asymmetrical. At sufficiently large amplitudes, a bistability region is observed. Measurements were conducted with a resonator, where a layer with the thickness of 15 mm was manufactured of a rubber-like polymer called plastisol. The shear modulus of the polymer at small deformations and the nonlinearity coefficient were determined according to the experimental dependence of mechanical stress on shear deformation. Oscillation amplitudes in the resonator attained values when the maximum shear deformations in the layer were 0.4–0.6, which provided an opportunity to observe nonlinear effects. Measured dependences of the resonance frequency on the oscillation amplitude corresponded to the calculated ones that were obtained at a smaller value of the nonlinear coefficient.     

Optical bistability and spatial resonator solitons based on exciton-polariton nonlinearity

We show experimentally optical bistability and the existence of bright and dark resonator solitons in the strong coupling regime between quantum-well excitons and the optical field in a semiconductor microcavity. The strong coupling results in a quasi-particle exciton-polariton, which gives access to positive and negative reactive and dissipative optical nonlinearities, as opposed to the usual room temperature semiconductor nonlinearities possessing essentially only one sign. The existence range and the properties of solitons can be varied widely by the detuning between polariton states and light frequency.     

Self pulsing inm dispersive optical bistability

We analyze the stability of the stationary solutions of dispersive optical bistability in a ring cavity for a homogeneously broadened atomic system. The analysis is performed in the limit αL ? 1, with $\text{C =}\text{αL}\text{2}\text{T}$ fixed. It is shown that in the dispersive case one can yield instability also when bistability is absent. This feature suggests that the dispersive case is more suitable than the purely absorptive one with respect to the observation of the self-pulsing behavior.     

Optical switching in a coupler with saturable nonlinearity

Abstact We report in this paper a numerical study of optical switching in couplers with saturable nonlinearity. Regions that characterize different coupling behaviour are revealed. It is shown that, in the presence of saturation, a Gaussian pulse should be used instead of solitons for negligible pulse splitting between the coupler arms. Nearly complete switching is possible depending on the input optical power and the index saturation parameter.     

Modes in the Fabry-Perot resonator with the Kerr nonlinearity

Summary The symmetric modes in the cavity of Fabry-Perot type filled by the medium with the Kerr nonlinearity are constructed. The field appears to be double periodic along the longitudinal axis.

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Riassunto Si costruiscono i modi simmetrici nella cavità del tipo di Fabry-Perot riempita dal mezzo con la non linearità di Kerr. Il campo risulta doppiamene periodico lungo l’asse longitudinale.

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Резюме Конструируются симметричные моды в резонаторе Фабри-Перо, заполненном средой с нелинейностью Керра. Оказывается, поле имеет двойную периодичность вдоль продольной оси.

     

Optical solitons and optical rogons of generalized resonant dispersive nonlinear Schrödinger's equation with power law nonlinearity

This paper obtains solitons and singular periodic solutions to the generalized resonant dispersive nonlinear Schrödinger’ equation with power law nonlinearity. There are several integration tools that are adopted to extract these solutions. They are simplest equation method, functional variable method, sine–cosine function method, tanh function method and the G′/G-expansion method. These integration techniques reveal bright and singular solitons as well as the corresponding singular periodic solutions to the nonlinear evolution equation. These solitons solutions are important in the nonlinear fiber optics community as well as in the study of rogue waves.     

Detection of low-concentration EGFR with a highly sensitive optofluidic resonator

A hollow-core metal-cladding waveguide(HCMW) optofluidic resonator that works based on a free-space coupling technique is designed. An HCMW can excite ultra-high-order modes(UOMs) at the coupled angle, which can be used as an optofluidic resonator to detect alterations of the epidermal growth factor receptor(EGFR)concentration. Theoretical analysis shows that the UOMs excited in the HCMW have a highly sensitive response to the refractive index(RI) variation of the guiding layer. An EGFR solution with a 0.2 ng/mL alteration is detected, and the RI variation caused by the concentration alteration is about 2.5 × 10~(-3).     

Optical dispersive bistability in media with forced girotropy

In this paper the results of an analysis concerning the course of optical dispersive bistability in media with forced girotropy (the Faraday effect) are presented. It is shown that radiation transmitted through a non-linear Fabry-Perot cavity reveals, apart from bistability of the intensity, bistable states of polarization. The elliptically polarized transmission radiation changes bistably not only the value of proportion of the semiaxes of the polarization ellipse and the orientation angle of its major semi-axis, but also the direction of the rotation of its electric vector.     

High-contrast dispersive readout of a superconducting flux qubit using a nonlinear resonator

We demonstrate high-contrast state detection of a superconducting flux qubit. Detection is realized by probing the microwave transmission of a nonlinear resonator, based on a SQUID. Depending on the driving strength of the resonator, the detector can be operated in the monostable or the bistable mode. The bistable operation combines high-sensitivity with intrinsic latching. The measured contrast of Rabi oscillations is as high as 87%; of the missing 13%, only 3% of the loss of contrast is unaccounted for. Experiments involving two consecutive detection pulses are consistent with preparation of the qubit state by the first measurement.     

Optical nonlinearity of CdS

The discovery and investigation of optically nonlinear behavior of CdS is reviewed. The development is described from nonlinear anti-Stokes excitation via the characterization of inelastic light scattering processes and the identification of high-density phenomena like biexciton creation, excitonic collisions, and electron-hole plasma generation towards very recent time-resolved gain, light-induced grating, and in particular optical bistability experiments. CdS is thus shown to allow for an extremely wide variety of different optically nonlinear processes and may be regarded as a model material for this field. Possible applications show up for several of the described phenomena.     

Optical pulse narrowing using a Fabry-Perot resonator

An optical pulse narrowing technique by spectral windowing using a Fabry-Perot resonator is demonstrated. A 150 ps pulse from a mode-locked Ar ion laser has been compressed by a factor of 2.7.     

Dynamics of localized waves with large amplitude in a weakly dispersive medium with a quadratic and positive cubic nonlinearity

The dynamics of localized waves is analyzed in the framework of a model described by the Korteweg-de Vries (KdV) equation with account made for the cubic positive nonlinearity (the Gardner equation). In particular, the interaction process of two solitons is considered, and the dynamics of a “breathing” wave packet (a breather) is discussed. It is shown that solitons of the same polarity interact as in the case of the Korteweg-de Vries equation or modified Korteweg-de Vries equation, whereas the interaction of solitons of different polarity is qualitatively different from the classical case. An example of “unpredictable” behavior of the breather of the Gardner equation is discussed.     

Optical dipole trap inside a laser resonator

We report the first realization, to our knowledge, of an optical dipole trap inside the active resonator of a laser. The concept, which is demonstrated with a CO2 laser (lambda = 10.6 microm), combines the advantages of optical power enhancement (up to 1.3-kW peak power) with the intrinsic stability of laser intensity as a result of the feedback of the active laser medium. Two kinds of trapping geometries are presented: a Gaussian trap in a transverse TEM00 mode and a boxlike transverse confinement in a superposition of transverse modes. In addition, longitudinal superlattices are created by two-frequency operation of the laser. Transfer efficiencies of up to 50% from a cesium magneto-optical trap are achieved. Storage times (7 = 0.3 s) are mainly limited by the background gas pressure. Possible sources of additional loss of atoms are discussed.     

Nonlinear equations for quasi-monochromatic waves near a caustic in a dispersive dissipative medium with cubic or quadratic nonlinearity

The behavior of a quasi-monochromatic nonlinear wave near a caustic is considered. Nonlinear ordinary differential equations for a dispersive dissipative medium with a cubic or quadratic nonlinearity are derived. For the latter medium, nonstationary equations describing it near the caustic are presented with allowance for the dissipative dispersive terms. These equations yield ordinary ones for quasi-monochromatic waves. The amplitude of the second harmonic is expressed in terms of the squared amplitude of the first harmonic. The amplitude of the second harmonic, as well as the solution as a whole, increases near the caustic.     

Optical bistability in a single-bus InGaAs micro-ring resonator array

In this paper, we investigate the optical bistability induced by optical nonlinearity in a compact parallel array of micro-ring resonators with radius of 5 μm. Due to the nature of perfect light confinement in this structure, resonance and accumulation process in a ring resonator and optical nonlinear effects, are observable even at small optical power (a few milliwatts). Different optical applications such as all-optical switching, optical memory devices, logic gates and modulators are possible, due to optical bistability in a ring resonator. Using alternative semiconductor compounds, instead of silicon that have weak nonlinear optical properties, we improve the performance of ring-resonator based devices. Here we use a polymer cladding layer with negative thermo-optic coefficient. Using this structure we can eliminate the temperature created nonlinearity which is a very slow process. Therefore, the switching speed increases from a few MHz to several tens of GHz. By plotting the transfer function of the resonator, a hysteresis loop is observed in a few milliwatts. Although, using a ring resonator array the bandwidth reduces, however, the width of the hysteresis loop and resolution between both steady state increases.     

Preparation and dispersive mechanism of highly dispersive ultrafine silver powder

Using ascorbic acid as the reducing agent, AgNO₃ as the source of Ag, the ultrafine silver powder was prepared by liquid-phase reduction method. The optimal conditions to prepare the ultrafine silver powder were obtained by studying the effects of following factors, such as the selection of dispersant, the doses of dispersant and pH, on the dispersibility of silver powder under other constant conditions. The pure ultrafine silver powder with quasi-spherical shape and mean size of 1.15 μm was synthesized under the optimal conditions of polyvinyl alcohol (PVA) as disperser, PVA/AgNO₃ mass ratio of 4:100 and pH 7 while maintaining other conditions exactly in the same circumstances, such as AgNO₃ concentration of 0.20 mol L⁻¹, ascorbic acid concentration of 0.15 mol L⁻¹ and reaction temperature of 40 °C. The ultrafine silver powder was characterized by SEM and XRD. And a PVA dispersive mechanism for preparing highly dispersive ultrafine silver powder, proved by the ultraviolet spectra, is that PVA absorbed on the surface of silver particles by coordination bond preventing the silver particles from diffusion and aggregation. In addition, the steric effect may help to reduce aggregation.     

Optical spatial solitons supported by photoisomerization nonlinearity in a polymer

We present a theory for a new type of optical spatial soliton that is based on the angle hole burning mechanism of photoisomerization in some polymers. We predict that the photoisomerization nonlinearity can support steady-state dark and bright spatial solitons in the polymer. We also discuss the dependence of the FWHM of the spatial soliton on wavelengths of the background beams and on the ratio of the intensity of the background beam to that of the signal beam.     

Optical soliton perturbation with quadratic-cubic nonlinearity using a couple of strategic algorithms

In this work, we derive bright, dark and singular soliton solutions to quadratic-cubic nonlinear media with perturbation terms being present. We perform the modified simple and the trial equation algorithms to the considered model. In addition, periodic singular wave solutions will be constructed by the integration schemes.