Passive Nonlinear Resonator Research Articles

Optical Parametric Oscillation with Ultra-Low Power Threshold in a Dimer of Active-Passive Cavities

Optical parametric oscillation can convert the input laser into a couple of coherent optical output with signal and idler frequencies. It is an important method for the realization of the broadband middle infrared tunable lasers. The optical parametric oscillation process depends on the ultra-fast non-linear response of matter to light with a certain pump power. Therefore, reducing the pump threshold of the optical parametric oscillation process and improving the energy conversion efficiency are of great significance to the study of non-linear optics. In this paper, we construct a dimer system that couples a passive non-linear resonator to an active resonator. Based on the dimer system, an ultra-low threshold optical parametric oscillation generation method is proposed. By coupling the gain pump mode, the non-linear effect is effectively enhanced, the pump power threshold is reduced to half of when there is no gain, and the energy conversion efficiency is increased. We believe this research provides a feasible method for a low-threshold tunable and easy-to-integrate optical parametric oscillation laser source.

A Position-Insensitive Wireless Power Transfer System Employing Coupled Nonlinear Resonators

Conventional magnetically coupled resonant wireless power transfer (WPT) systems suffer from a significant performance degradation as the coupling factor between transmit and receive coils changes from its optimum value. In this article, a new WPT circuit that consists of two passive nonlinear resonators in both the transmitter and receiver is proposed. The circuit can adapt well to a wide range of coupling factor variations to provide constant output power without using any active control circuitry, frequency tuning, or complicated coil configurations. Both analytical and numerical simulations for the WPT circuit are provided. A 60-W nonlinear WPT prototype circuit operating at 1.5 MHz is designed, fabricated, and measured. The results show that the WPT system based on the proposed circuit is capable of maintaining almost a constant output power, while the distance between the coils varies up to 15 cm, a significant performance improvement compared to the linear WPT circuit tested under the same conditions.

Competing Turing and Faraday Instabilities in Longitudinally Modulated Passive Resonators.

We experimentally investigate the interplay of Turing (modulational) and Faraday (parametric) instabilities in a bistable passive nonlinear resonator. The Faraday branch is induced via parametric resonance owing to a periodic modulation of the resonator dispersion. We show that the bistable switching dynamics is dramatically affected by the competition between the two instability mechanisms, which dictates two completely novel scenarios. At low detunings from resonance, switching occurs between the stable stationary lower branch and the Faraday-unstable upper branch, whereas at high detunings we observe the crossover between the Turing and Faraday periodic structures. The results are well explained in terms of the universal Lugiato-Lefever model.

Spatial optical solitons in microstructured cavities

We present a detailed study of the dynamics of light in passive nonlinear resonators with shallow and deep intracavity periodic modulation of the refractive index in both longitudinal and transverse directions of the resonator. We investigate solutions localized in the transverse direction (so-called Bloch cavity solitons) by means of envelope equations for underlying linear Bloch modes and solving Maxwell’s equations directly. Using a round-trip model for forward and backward propagating waves we review different types of Bloch cavity solitons supported by both focusing (at normal diffraction) and defocussing (at anomalous diffraction) nonlinearities in a cavity with a weak-contrast modulation of the refractive index. Moreover, we identify Bloch cavity solitons in a Kerr-nonlinear all-photonic crystal resonator solving Maxwell’s equations directly. In order to analyze the properties of Bloch cavity solitons and to obtain analytical access we develop a modified mean-field model and prove its validity. In particular, we demonstrate a substantial narrowing of Bloch cavity solitons near the zero-diffraction regime. Adjusting the quality factor and resonance frequencies of the resonator optimal Bloch cavity solitons in terms of width and pump energy are identified.

Theory of Bloch cavity solitons

We present a detailed study of light dynamics in passive nonlinear resonators with shallow intracavity periodic modulation of the refractive index in both longitudinal and transverse directions of the resonator. Specifically, we concentrate on the nonlinear envelopes of dissipative Bloch modes, localized in the transverse plane of the resonator, the so-called Bloch cavity solitons, predicted recently in K. Staliunas et al. [Phys. Rev. Lett. 101, 153903 (2008)]. Bloch cavity solitons, being dissipative structures, are attractors, therefore they can be excited from a wide range of initial conditions (the attractor basin) depending on the system's parameters. A unique property of Bloch cavity solitons is that they are envelopes of waves with tailored diffraction. Using the round-trip model for forward- and backward-propagating waves we reveal different types of Bloch cavity solitons supported by both focusing (at normal diffraction) and defocusing (at anomalous diffraction) nonlinearities. We show also the coexistence of solitons bifurcating from different Bloch wave dispersion branches. In order to analyze the properties of Bloch cavity solitons and to obtain an analytical access we develop a modified mean-field model and prove its validity. In particular, we demonstrate substantial narrowing of Bloch cavity solitons near the zero-diffraction regime.

Transverse structures in a sodium-filled Fabry-Pérot resonator—II. Interpretation of experimental results

We provide a heuristic physical interpretaion of experimental results given in a preceding paper in this issue, on pattern formation in a nonlinear confocal Fabry-Pérot resonator. The basic physical principles governing a resonator with a self-induced, intracavity lens, well applicable to a nonlinear medium dominated by diffusion, are shown to be sufficient to explain the salient features of the structures that can be formed in the nonlinear system for weak nonlinearities, and give useful guidance in the case of stronger nonlinearities as well. This interpretation highlights the basics of the interplay between the nonlinear medium and the optical cavity, thereby elucidating the mechanisms that control pattern formation in a passive nonlinear resonator. The analysis of the experimentally observed symmetries, as a function of the beam incoupling and of the other experimental conditions, shows that the crucial parameters that control the topological properties of patterns are the modal phases, especially the excitation phases.

Phase effects in passive nonlinear resonators

New effects in passive nonlinear resonators are considered. It is shown that effective suppression of phase distortions in systems of this kind resembles phase conjugation. Control of the phase of a light wave inside such resonators can provide an active means for modifying the spatial characteristics of the output radiation by producing optical fields with the required structure.