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We predict subharmonic entrainment of breather-soliton oscillations to a periodic perturbation at the round-trip time ${T}_{R}$ in Kerr-nonlinear optical resonators; an integer ratio ${T}_{b}/{T}_{R}=N\ensuremath{\gg}1$ results for breathing period ${T}_{b}$. Rigid entrainment is observed with intermediate finesse ($\mathcal{F}\ensuremath{\sim}30--40$) for $N$ up to 20, and we propose a way to realize higher entrainment ratios at higher finesse. This nontrivial synchronization across the widely separated timescales of the photon lifetime and round-trip time points to a new direction for research in this field and may find application, for example, in the measurement of a pulse train repetition rate that is electronically inaccessible.

Using aluminum-nitride photonic-chip waveguides, we generate optical-frequency-comb supercontinuum spanning from 500 nm to 4000 nm with a 0.8 nJ seed pulse, and show that the spectrum can be tailored by changing the waveguide geometry. Since aluminum nitride exhibits both quadratic and cubic nonlinearities, the spectra feature simultaneous contributions from numerous nonlinear mechanisms: supercontinuum generation, difference-frequency generation, second-harmonic generation, and third-harmonic generation. As one application of integrating multiple nonlinear processes, we measure and stabilize the carrier-envelope-offset frequency of a laser comb by direct photodetection of the output light. Additionally, we generate ~0.3 mW in the 3000 nm to 4000 nm region, which is potentially useful for molecular spectroscopy. The combination of broadband light generation from the visible through the mid-infrared, combined with simplified self-referencing, provides a path towards robust comb systems for spectroscopy and metrology in the field., 8 pages, 5 figures

Building upon previous work, several new thermodynamic properties are found for classical electromagnetic random radiation in thermal equilibrium with classical electric dipole harmonic oscillators. Entropy is calculated as a function of temperature and as a function of the positions of the dipole oscillators. In the process, a new derivation is obtained for what is often called Wien's displacement law. The original derivation of this law makes a number of implicit assumptions not found in the present derivation, which prevents the original analysis from being sufficiently general to address an important class of thermal radiation spectrum candidates: namely, those that are nonzero at T=0. While leading up to the entropy calculation, a number of other thermodynamic properties are deduced. For example, a natural development is presented for reformulating the St\'efan-Boltzmann law to correspond to experimental observations about changes in thermal radiation energy. Also, the Rayleigh-Jeans spectrum is shown to conflict with basic concepts of thermodynamic processes, and asymptotic limits are found for the spectrum of classical electromagnetic thermal radiation. One asymptotic restriction arises from the demand of finite specific heat for thermal radiation. This restriction is sufficient to ensure that the classical electrodynamic system of dipole oscillators and thermal radiation must obey the third law of thermodynamics. The calculations described here include full nonperturbative evaluations of retarded van der Waals thermodynamic functions.

A new fundamental thermodynamic property has been proved for classical electromagnetic zero-point radiation. Aside from a proportionality constant, classical electromagnetic zero-point radiation is shown here to possess the unique spectrum that is suitable for establishing a thermal equilibrium state with a set of fluctuating classical electric dipole harmonic oscillators at the temperature of absolute zero. As a consequence of this analysis, one can see that according to the fundamental thermodynamic definition of absolute zero temperature, the following traditional view in thermodynamics is an unnecessary thermodynamic restriction: namely, that all fluctuating motion and radiation must vanish at T=0 for classical physical systems. Indeed, as shown here, this restriction can violate the third law of thermodynamics if the spectrum reduces to zero by being proportional to T. The analysis in this article involves the calculation of (1) the change in internal energy, (2) the work done, and (3) the heat radiated for a quasistatic displacement of electric dipole nonrelativistic harmonic oscillators immersed in random classical electromagnetic radiation. The calculations include full nonperturbative evaluations of retarded van der Waals thermodynamic functions.

Here we show that a wide range of states of phases and amplitudes exist for a circularly polarized (CP) plane wave to act on a classical hydrogen model to achieve infinite times of stability (i.e., no orbital decay due to radiation reaction effects). An analytic solution is first deduced to show this effect for circular orbits in the nonrelativistic approximation. We then use this analytic result to help provide insight into detailed simulation investigations of deviations from these idealistic conditions. By changing the phase of the CP wave, the time t(d) when orbital decay sets in can be made to vary enormously. The patterns of this behavior are examined here and analyzed in physical terms for the underlying but rather unintuitive reasons for these nonlinear effects. We speculate that most of these effects can be generalized to analogous elliptical orbital conditions with a specific infinite set of CP waves present. The paper ends by briefly considering multiple CP plane waves acting on the classical hydrogen atom in an initial circular orbital state, resulting in "jump-like" and "diffusion-like" orbital motions for this highly nonlinear system. These simple examples reveal the possibility of very rich and complex patterns that occur when a wide spectrum of radiation acts on this classical hydrogen system.

We analyze the proposal that gravity may originate from a van der Waals type of residual force between particles due to the vacuum electromagnetic zero-point field. Starting from the Casimir-Polder integral, we show that the proposed approach can be analyzed directly, without recourse to approximations previously made. We conclude that this approach to Newtonian gravity does not work, at least not with this particular starting point. Only by imposing different or additional physical constraints, or by treating the underlying dynamics differently than what are embodied in the inherently subrelativistic Casimir-Polder integral, can one expect to escape this conclusion.

On considere un systeme constitue de deux oscillateurs harmoniques simples dipolaires classiques spatialement separes qui sont uniformement acceleres a travers un rayonnement au point zero electromagnetique classique et qui interagissent entre eux par un rayonnement electromagnetique emis