Nonlinear Ring Cavity Research Articles

Linewidth-narrowing and frequency noise reduction of Brillouin fiber laser cavity operating at 1-µm

We report on a stabilized single-frequency Brillouin fiber laser operating at 1.06 µm by means of a passive highly nonlinear fiber ring cavity combined with a phase-locking loop scheme. We show significant linewidth narrowing (below 1-kHz) as well as frequency noise reduction compared to that of the initial pump in our mode-hop free Brillouin fiber laser.

Nonlinear frequency response of the multi-resonant ring cavities

A convenient for practical use new theoretical approach describing a nonlinear frequency response of the multi-resonant nonlinear ring cavities (RC) to an intense monochromatic wave action is developed. The approach closely relates the many-valuednesses of the RC frequency response and the dispersion relation of a waveguide, from which the cavity is produced. Arising of the multistability regime in the nonlinear RC is treated. The threshold and the dynamic range of the bistability and tristability regimes for an optical ring cavity with the Kerr nonlinearity are derived and discussed.

Bose-Hubbard hopping due to resonant Rayleigh scattering.

We show theoretically that dynamic behavior of light confined in the modes of a nonlinear optical ring cavity characterized by resonant Rayleigh scattering can be described using the Bose-Hubbard model. Nonlinear interaction between clockwise and counterclockwise optical modes results in instability and intermode hopping occurring at a rate defined by the frequency separation of the Rayleigh doublet harmonics. Hopping may lead to an instability and breathing behavior of a Kerr frequency comb observed in the cavity.

Period-Doubling and Quadrupling Bifurcation of Vector Soliton Bunches in a Graphene Mode Locked Fiber Laser

Period-doubling bifurcation and period-quadrupling bifurcation of vector soliton pulses in a graphene mode locked fiber laser is experimentally observed and investigated. Not only single vector soliton but also vector soliton bunches as a unity are found to exhibit period-doubling and period-quadrupling bifurcation. The experimental results suggest that period-doubling and quadrupling bifurcation are intrinsic features of the pulses circulating in a nonlinear ring cavity, which are independent of the properties of the mode-locker in the fiber lasers.

Coherent and incoherent seeding of dissipative modulation instability in a nonlinear fiber ring cavity.

We investigate the coherent or incoherent seeding of dissipative modulation instability (MI) in a nonlinear fiber ring cavity. By varying wavelength and degree of coherence of the seed signal across the MI gain band, we observe a strong sensitivity of the resulting MI sidebands in terms of bandwidth and amplification. Both spectral and temporal characterizations are performed to reveal intensity coherence properties (over a single round-trip) of the generated temporal patterns. Experimental observations are well confirmed by numerical simulations. Our results provide new insights into the control of dissipative MI through a specific seeding in optical resonators with a moderate free-spectral range. In particular, a large tunability of the subsequent Kerr comb spacing is achieved by means of the early transient stage of seeded MI growth.

Multiple four-wave mixing and Kerr combs in a bichromatically pumped nonlinear fiber ring cavity.

We report numerical and experimental studies of multiple four-wave mixing processes emerging from dual-frequency pumping of a passive nonlinear fiber ring cavity. We observe the formation of a periodic train of nearly background-free soliton pulses associated with Kerr frequency combs. The generation of resonant dispersive waves is also reported.

Localized plateau beam resulting from strong nonlocal coupling in a cavity filled by metamaterials and liquid-crystal cells

We investigate the formation of a localized plateau beam in the transverse section of a nonlinear optical ring cavity filled with a metamaterial and a nonlocal medium such as a nematic liquid crystal. We show that, far from the modulational instability regime, localized structures with a varying width may be stable in one and two-dimensional settings. The mechanism of stabilization is related with strong nonlocal coupling mediated by a Lorentzian type of kernel. We show that there exists stable bright and dark localized structures. A reduction of Lugiato--Lefever equation in the regime close to the nascent bistability allows us to analytically derive a simple formula for the width of localized structures in one-dimensional systems. Direct numerical simulations of the dynamical model agree with the analytical predictions.

Investigation of the optical bistability in the PMMA polymer doped with MNA

The optical bistability (OB) of PMMA polymer doped with 2-Methyl-4-Nitroaniline (MNA) thin films on Mach–Zehnder interferometer nonlinear ring cavity with applied external feedback was investigated in five thicknesses. The measurements were performed at 532nm using a Nd:YAG CW laser with irradiation of 300mW. An optical bistability hysteresis was obtained because of charge transfer in benzene ring in MNA's structure. It is demonstrated that although, the gain of optical bistability improved using external feedback for thinner samples. While, in thicker samples, the local thermal effect decreased the gain and had negative effect on OB.

Nonlinear dynamics of modulation instability in distributed resonators under external harmonic driving

We study the regimes of complex field dynamics upon modulation instability in distributed nonlinear resonators under external harmonic driving. Two regimes are considered: the regime of a nonlinear ring cavity, described by nonlinear Schrodinger equation (NLS) with a delayed boundary condition, and the regime of a one-dimensional Fabri-Perot cavity, described by a system of coupled NLS for the forward and backward waves. Theoretical stability analysis of stationary forced oscillations is carried out. The results of numerical simulation of transition to chaos with increasing input intensity are presented.

Dynamics of a nonlinear ring cavity: Excitability and coherent resonance

The phenomena of excitability and coherent resonance in a nonlinear ring cavity in the presence of excitons and biexcitons are considered. A bifurcation analysis of the dynamics of the nonlinear ring cavity indicates that both self-pulsation and excitability can exist in the system. It is demonstrated that coherent resonance can be observed in an excitable exciton-biexciton system in the ring cavity. The optimum conditions for the manifestation of these phenomena are investigated, and their possible applications are discussed.

Semiclassical quantization of an optical pulse confined in a Kerr-effect nonlinear ring cavity

We obtain two stationary solutions for an intense optical pulse propagating in a Kerr-effect nonlinear ring cavity using elliptic functions associated with a parameter $m$. The solutions may be associated with distinct phases of the system, the transition from one to the other being dictated by an energy ratio. Semiclassical quantization reveals excitations that are quantized rotational states for the spatially constant solution and $N$-particle bound states for the soliton solution. On invoking periodic boundary conditions, a constraint relating the number of particles, wavelength, and $m$ emerges. This constraint fundamentally modifies the binding energy of the soliton for a large range of $m$. At the phase transition point, the energy undergoes a discontinuity in both value and derivative, a conclusion that differs markedly from results of a mean-field calculation.

Three-dimensional structures in nonlinear cavities containing left-handed materials

We study the coupling between negative diffraction and direct dispersion in a nonlinear ring cavity containing slabs of Kerr nonlinear right-handed and left-handed materials. Within the mean field approximation, we show that a portion of the homogeneous response curve is affected by a three-dimensional modulational instability. We show numerically that the light distribution evolves through a sequence of three-dimensional dissipative structures with different lattice symmetry. These structures are unstable with respect to the upswitching process, leading to a premature transition to the upper branch in the homogeneous hysteresis cycle.

Pattern formation by spatially incoherent light in a nonlinear ring cavity

Modulation instability and pattern formation by spatially incoherent light is investigated experimentally in a nonlinear ring cavity using a photorefractive strontium barium niobate crystal as the nonlinear medium. A step-like threshold for the onset of pattern formation is observed experimentally for the case of high optical feedback. When compared to the case without feedback, this threshold is shifted towards smaller nonlinearities and a significant increase of the modulation degree of the obtained patterns is obtained. Our measurements also show that, above threshold, the dominating spatial frequency of the patterns decreases monotonically with both increasing nonlinearity and increasing feedback.

Broadband source generated by stimulated Raman scattering and four-wave mixing in a highly nonlinear optical fiber ring cavity.

A novel high-power broadband source based on the combined action of stimulated Raman scattering and parametric four-wave mixing in a highly nonlinear dispersion-shifted fiber ring cavity is investigated experimentally. An output spectrum of 1510-1580 nm with a stable power of 91 mW is demonstrated with a dual-wavelength pumping scheme.

Investigation of chaotic dynamics of a nonlinear ring cavity under two-frequency external driving

Complex dynamics of a nonlinear ring cavity filled by medium with cubic phase nonlinearity under multi-frequency driving is considered. System оf coupled Ikeda maps to describe the dynamics of spectral components was derived. Regimes of steady-state oscillations and their stability conditions are analyzed. The results оf numerical simulation of transition to chaos in the case of two-frequency driving are presented.

Excitability of excitons and biexcitons in a ring cavity.

We discuss the excitable behavior of excitons and biexcitons in a nonlinear optical ring cavity. The nonlinearity is due to the process of the creation of biexcitons by photon-assisted conversion of excitons. In the bifurcation analysis a region where a saddle point is close to an equilibrium has been found. In this region the system shows excitability. It is shown that the mechanism of the excitable behavior of excitons and biexcitons in a ring cavity is different from that of two-level atoms in the same system. The possible applications of an excitable ring cavity are discussed.

Parallel communication with optical spatiotemporal chaos

We investigate the potential of chaotic-optical wavefronts as information carriers in parallel communication systems. Numerical simulations show that broad-area nonlinear ring cavities generate spatiotemporally chaotic signals which allow encoding and decoding of data in space and time. The synchronization process on which the scheme is based, along with the efficiency of the communication system, are examined.

Spatiotemporal communication with synchronized optical chaos.

We propose a model system that allows communication of spatiotemporal information using an optical chaotic carrier waveform. The system is based on broad-area nonlinear optical ring cavities, which exhibit spatiotemporal chaos in a wide parameter range. Message recovery is possible through chaotic synchronization between transmitter and receiver. Numerical simulations demonstrate the feasibility of the proposed scheme, and the benefit of the parallelism of information transfer with optical wave fronts.

Pattern formation and competition in a nonlinear ring cavity

Spontaneous pattern formation and competition in a nonlinear ring cavity are studied. Complex patterns arising from static and Hopf bifurcations and Hopf-static interactions have been numerically observed and analysed. Among them are flower-like patterns, alternating rolls and oscillating hexagonal structures.

Three-dimensional crystals and localized structures in diffractive and dispersive nonlinear ring cavities

When diffraction operates together with chromatic dispersion, the type II second-harmonic generation exhibits a three-dimensional (3D) modulational instability leading to the formation of 3D periodic solutions travelling at the group velocity of light within the cavity. Numerical analysis reveals the occurrence of 3D localized structures in the form of isolated light drops or cylinders. They are specific to the parameter range where 3D stable periodic patterns coexist with the single homogeneous steady state.