Search results for " optical fiber"
showing 10 items of 327 documents
Spatial localization and pattern formation in discrete optomechanical cavities and arrays
2020
We investigate theoretically the generation of nonlinear dissipative structures in optomechanical (OM) systems containing discrete arrays of mechanical resonators. We consider both hybrid models in which the optical system is a continuous multimode field, as it would happen in an OM cavity containing an array of micro-mirrors, and also fully discrete models in which each mechanical resonator interacts with a single optical mode, making contact with Ludwig & Marquardt [Phys. Rev. Lett. 101, 073603 (2013)]. Also, we study the connections between both types of models and continuous OM models. While all three types of models merge naturally in the limit of a large number of densely distribu…
Phase Locking between Two All-Optical Quantum Memories.
2020
Optical approaches to quantum computation require the creation of multi-mode photonic quantum states in a controlled fashion. Here we experimentally demonstrate phase locking of two all-optical quantum memories, based on a concatenated cavity system with phase reference beams, for the time-controlled release of two-mode entangled single-photon states. The release time for each mode can be independently determined. The generated states are characterized by two-mode optical homodyne tomography. Entanglement and nonclassicality are preserved for release-time differences up to 400 ns, confirmed by logarithmic negativities and Wigner-function negativities, respectively.
Backaction-evading measurement of entanglement in optomechanics
2019
We propose here a fully backaction-evading scheme for the measurement of the entanglement between two nanomechanical resonators. The system, which consists of two mechanical oscillators, coupled to a single mode of an electromagnetic resonant cavity through a radiation-pressure interaction term, is driven by two pump tones and four detection tones. As previously discussed in the literature, the former induce entanglement between the two mechanical oscillators, while we show here that a specific choice of phase and amplitude of the detection tones allows for direct pairwise reconstruction of the collective quadrature fluctuations of the mechanical oscillators belonging to quantum-mechanics-f…
Optical Bloch-mode-induced quasi phase matching of quadratic interactions in one-dimensional photonic crystals
2004
We examine in detail the quasi-phase-matching process obtained as a stationary modulation of the fundamental field at the band edge of a finite one-dimensional photonic crystal. The treatment is carried out in terms of the structure Bloch waves and fully explains the behavior of second-harmonic generation in the grating. An integrated microstructured AlGaAs mesa waveguide is proposed that gives efficient second-harmonic and difference-frequency generation in virtue of the combined presence of a periodic modulation of the fundamental-field amplitude and of the photonic bandgap edge.
Steady-state emission and stability of a single-mode two-level Fabry-Perot cavity laser
1997
Abstract An analytical steady-state solution for a single-mode homogeneously-broadened two-level Fabry-Perot laser, valid for any field intensity, cavity detuning and level-population decay rates, is obtained. A power-series expansion of this solution allows to perform a linear stability analysis which reveals the existence of two Hopf bifurcations instead of one as in unidirectional ring lasers. These bifurcations delimit the domain of unstable emission of the laser with respect to small perturbations. The instability threshold for hard-mode excitation is higher than in a ring laser, although introduction of a small definite detuning makes them similar. The time-dependent behaviour above t…
Multimode squeezing of frequency combs
2006
We have developed a full multimode theory of a synchronously pumped type-I optical parametric oscillator. We calculate the output quantum fluctuations of the device and find that, in the degenerate case (coincident signal and idler set of frequencies), significant squeezing is obtained when one approaches threshold from below for a set of well-defined ``supermodes,'' or frequency combs, consisting of a coherent linear superposition of signal modes of different frequencies which are resonant in the cavity.
Stability of gyrotron operation in very high-order modes
2012
This study was motivated by the desire to increase the power, which can be delivered by gyrotrons in long pulse and continuous regimes. Since the admissible power level is determined by the density of ohmic losses in resonator walls, to increase the radiated power a gyrotron should operate in higher order modes. Using an existing gyrotron developed for plasma experiments in the International Thermonuclear Experimental Reactor as a base model, the stability of operation of such a gyrotron in modes with larger number of radial variations was studied. It is shown that the power level achievable in such gyrotrons in stable single mode regimes is close to 1.5 MW. The power level 1.7–1.8 MW can b…
Photonic transfer through subwavelength optical waveguides
1998
Optical tunneling effect through dielectric junctions with subwavelength transverse sizes has been demonstrated some years ago. In this letter, we demonstrate how similar effects can be exploited to perform photonic transfer through a subwavelength optical wave guide (SOW) by structuring its optical index along the direction of propagation. The optical transmittance of the SOW is computed self-consistently in direct space through the numerical solution of a Dyson equation. We apply this scheme to investigate the optical properties of different SOW architectures. Even under total internal reflection, in which the light is coupled to the SOW by an evanescent mode, an efficient optical transfe…
Adaptive Kerr-Assisted Transverse Mode Selection in Multimode Fibers
2019
Multimode optical fibers (MMFs) have recently regained interest because of the degrees of freedom associated with their different eigenmodes. In the nonlinear propagation regime in particular, new phenomena have been unveiled in graded-index (GRIN) MMFs such as geometric parametric instabilities and Kerr beam self-cleaning [1, 2]. The speckled pattern observed at the output of the MMF at low powers, is transformed at high powers into a bell-shaped beam close to the fundamental mode. Recent work has also demonstrated that Kerr beam self-cleaning can lead to a low-order spatial mode, different from a bell-shape, by adjusting the laser beam in-coupling conditions [3]. An attractive way to syst…
Analysis of Inhomogeneously Dielectric Filled Cavities Coupled to Dielectric-Loaded Waveguides: Application to the Study of NRD-Guide Components
2004
In this paper, we present two contributions. First, we develop a computationally efficient technique for the full-wave characterization of inhomogeneously dielectric-filled cavities connected to inhomogeneously dielectric-loaded waveguides. This method is based on the expansion of the electromagnetic field within the cavity in terms of their solenoidal and irrotational modes. The presented formulation allows the treatment of hybrid modes in the waveguide ports, where the definition of a characteristic modal impedance or admittance is not possible. The multimode scattering matrix of the structure is computed throughout an efficient implementation of the orthonormal-basis method for the calcu…