Regime Of Parametric Amplification Research Articles

Interplay between gain and loss in arrays of nonlinear plasmonic nanoparticles: toward parametric downconversion and amplification.

With the help of a theoretical model and finite-difference time-domain (FDTD) simulations based on the hydrodynamic-Maxwell model, we examine the effect of difference-frequency generation (DFG) in an array of L-shaped metal nanoparticles (MNPs) characterized by intrinsic plasmonic nonlinearity. The outcomes of the calculations reveal the spectral interplay between gain and loss in the vicinity of the fundamental frequency of the localized surface plasmon resonances. Subsequently, we identify different array thicknesses and pumping regimes facilitating parametric amplification and spontaneous parametric downconversion. Our results suggest that the parametric amplification regime becomes feasible on a scale of hundreds of nanometers and spontaneous parametric downconversion on the scale of tens of nanometers, opening up new exciting opportunities for developing building blocks of photonic metasurfaces.

Cascaded interactions mediated by terahertz radiation.

We investigate a regime of parametric amplification in which the pump and signal waves are spectrally separated by only a few hundreds of GHz frequency - therefore resulting in a sub-THz frequency idler wave. Operating in this regime we find an optical parametric amplifier (OPA) behavior which is highly dissimilar to conventional OPAs. In this regime, we observe multiple three-wave mixing processes occurring simultaneously which results in spectral cascading around the pump and signal wave. Via numerical simulations, we elucidate the processes at work and show that cascaded optical parametric amplification offers a pathway toward THz-wave generation beyond the Manly-Rowe limit and toward the generation of high-energy, sparse frequency-combs.

Laser phase noise effects on the dynamics of optomechanical resonators

We investigate theoretically the influence of laser phase noise on the cooling and heating of a generic cavity optomechanical system. We derive the back-action damping and heating rates and the mechanical frequency shift of the radiation-pressure-driven oscillating mirror, and derive the minimum phonon occupation number for small laser linewidths. We find that, in practice, laser phase noise does not pose serious limitations to ground-state cooling. Additionally, we explore the regime of parametric amplification where coherent oscillations of the mirror are realizable. It is found that heating from laser phase noise is of significance and can cause the onset of instabilities. We then consider the effects of laser phase noise in a parametric cavity driving scheme that minimizes the back-action heating of one of the quadratures of the mechanical oscillator motion. Laser linewidths, narrow compared to the decay rate of the cavity field, do not pose any significant problems in an experimental setting, but broader linewidths limit the practicality of this back-action evasion method.

Action of the gravitational field on the dynamical Casimir effect

In this paper, we analyze the action of the gravitational field on the dynamical Casimir effect. We consider a massless scalar field confined in a cuboid cavity placed in a gravitational field described by a static and diagonal metric. With one of the plane mirrors of the cavity allowed to move, we compute the average number of particles created inside the cavity by means of the Bogoliubov coefficients computed through perturbative expansions. We apply our result to the case of an oscillatory motion of the mirror, assuming a weak gravitational field described by the Schwarzschild metric. The regime of parametric amplification is analyzed in detail, demonstrating that our computed result for the mean number of particles created agrees with specific associated cases in the literature. Our results, obtained in the framework of the perturbation theory, are restricted, under resonant conditions, to a short-time limit.

Dynamic radiation force of acoustic waves on solid elastic spheres

The present study concerns the dynamic radiation force on solid elastic spheres exerted by a plane wave with two frequencies (bichromatic wave) considering the nonlinearity of the fluid. Our approach is based on solving the wave scattering for the sphere in the quasilinear approximation within the preshock wave range. The dynamic radiation force is then obtained by integrating the component of the momentum flux tensor at the difference of the primary frequencies over the boundary of the sphere. Effects of the fluid nonlinearity play a major role in dynamic radiation force, leading it to a regime of parametric amplification. The developed theory is used to calculate the dynamic radiation force on three different solid spheres (aluminum, silver, and tungsten). The obtained spectrum of dynamic radiation force presents resonances with larger amplitude and better shape than those exhibited in static radiation force. Applications of the results to some elasticity imaging techniques based on dynamic radiation force will be presented.

Dynamic radiation force of acoustic waves on solid elastic spheres

The present study concerns the dynamic radiation force on solid elastic spheres exerted by a plane wave with two frequencies (bichromatic wave) considering the nonlinearity of the fluid. Our approach is based on solving the wave scattering for the sphere in the quasilinear approximation within the preshock wave range. The dynamic radiation force is then obtained by integrating the component of the momentum flux tensor at the difference of the primary frequencies over the boundary of the sphere. Results reveal that effects of the nonlinearity of the fluid play a major role in dynamic radiation force leading it to a parametric amplification regime. The developed theory is used to calculate the dynamic radiation force on three different solid spheres (aluminum, silver, and tungsten). Resonances are observed in the spectrum of the force on the spheres. They have larger amplitude and better shape than resonances present in static radiation force.

Polariton spin dynamics in III–V semiconductor microcavities

Time resolved measurements have been performed on a III–V semiconductor microcavity in a two beam configuration. Resonant excitation of the lower polariton branch in the parametric amplification regime is provided by a CW laser impinging at 16.5o and the system is subsequently perturbed via a pulsed laser for different angles of incidence. The polarization state of the emission at k‖ = 0 is investigated for different polarization combinations of the CW and pulsed laser. We discuss the interplay between these beams in affecting the polariton spin dynamics. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Theory of electric force microscopy in the parametric amplification regime

We propose to use a parametric amplification regime for small charge or potential difference detection in electric force microscopy. First we give a simple method to accurately estimate the instability domains of the oscillating system. Then we establish general and fully analytical expressions of the parametric amplification gain, and discuss the optimal parameter values which must be used for voltage or charge detection. We show that even in conventional Kelvin probe force microscopy the parametric effect should be taken into account.

Spin dynamics of interacting exciton polaritons in microcavities

We present the theory of spin relaxation of exciton polaritons treated as a gas of weakly interacting bosons. The model is based on the spin density matrix approach in the Born-Markov approximation. In its framework we have described the spin and energy relaxation of exciton-polaritons in semiconductor microcavities accounting for polariton-polariton and polariton-acoustic phonon scattering. We include various mechanisms of spin relaxation linked with the fine structure of the polaritons. The kinetic equation for time-dependent intensity and polarization of light emitted by the microcavities both at resonant and nonresonant pumping is obtained. The parametric amplification regime, in which the resonant polariton-polariton scattering plays the major role, is specifically analyzed. We show that the polarization plane of the emitted light can rotate as a function of the polarization degree of the pumping light which is a manifestation of the ``spin-optronic'' effect of self-induced Larmor precession of polariton pseudospins.

Polariton parametric amplifier coherent dynamics

The polariton coherent dynamics in the parametric amplification regime is studied experimentally in a II–VI semiconductor microcavity, using angle-resolved four-wave mixing. We observe a strong reduction of the pump polarization dephasing time under excitation at the magic angle above the parametric amplification threshold. Our observations are analyzed by calculating numerically the coupled rate equations for the signal, pump and idler polariton fields. This allows us to interpret our observations in terms of time-dependent pump depletion. We find that the coherent dynamics above the threshold is the result of a complex interplay between parametric amplification and collision broadening.

Statistics of polaritons in microcavities

We discuss the quantum statistical properties of exciton-polaritons in semiconductor microcavities. The nonlinear dynamics is treated within a model of interacting bosons for the signal, pump and idler modes. We focus on the regime of parametric amplification below threshold. We present the time evolution of the signal and idler modes towards their stationary solutions and evaluate the amount of squeezing of the radiation emitted out of the microcavity in a configuration, which is relevant for experiments. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Statistics of polaritons in the nonlinear regime

We discuss the quantum statistical properties of exciton polaritons in semiconductor microcavities. The nonlinear dynamics is treated within a model of interacting bosons for the signal, pump, and idler modes. We focus on the regime of parametric amplification below threshold. We present the time evolution of the signal and idler modes towards their stationary solutions and discuss their statistical properties. In particular, we evaluate the amount of squeezing of the radiation emitted out of the microcavity in a configuration, which may be relevant for experiments.

II–VI semiconductor microcavity angle‐resolved coherent dynamics

We used angle-resolved time-integrated four-wave mixing to study the pump dynamics in a II–VI semiconductor microcavity polariton parametric amplifier. The low-energy polariton dephasing time decreases at large angles when the excitonic reservoir becomes accessible to polariton–polariton scattering. Additionally, in the parametric amplification regime, with phase matching for the polariton–polariton scattering at the magic angle, we observe a strong reduction of the FWM decay time. Numerical analysis of the polariton coherent dynamics in this regime allows to interpret the observed features in terms of time dependent pump depletion.