Search results for "Bistability"
showing 10 items of 124 documents
Combined impacts of the Allee effect, delay and stochasticity: Persistence analysis
2020
Abstract We study a combined influence of the Allee effect, delay and stochasticity on the base of the phenomenological Hassell mathematical model of population dynamics. This bistable dynamical model possesses a wide variety of regimes, both regular and chaotic. In the persistence zone, these regimes coexist with the trivial equilibrium that corresponds to the extinction of the population. It is shown that borders of the persistence zone are defined by the crisis and saddle-node bifurcation points. Noise-induced transitions from the persistence to the extinction are studied both numerically and analytically. Using numerical modeling, we have found that the persistence zone can decrease and…
Observation of a nonlinear microfiber resonator
2008
Measurements of the intensity transfer function of a silica microfiber resonator are shown to follow a wide variety of hysteresis cycles, depending on the cavity detuning and the scanning frequency of the range of input powers. We attribute these observations to a nonlinear phase shift of thermal origin and provide a simple model that reproduces well our measurements. The response time is found to be around 0.6 ms.
Non-Linear Optical Properties of Hybridized Surface Plasmon Polaritonic Crystals: Observation of Optical Bistability
2007
Summary form only given. The use of surface plasmons (SP) is recognized as being central to the development of nanoscale assemblies of photonic and opto-electronic devices. This is motivated by the spatially confined nature of these electromagnetic waves as well as their resonant behavior. Amongst plasmonic supporting structures, surface plasmonic crystals (SPCs) draw particular interest because of their tailored optical properties. A geometry common to SPCs consists in a periodic arrangement of holes or slits in a metal film. Their complex optical response is then governed by coherent interactions between Bloch modes at the film's interfaces and modes supported by the holes or slits. These…
Stochastic resonance in a tunnel diode.
1994
We study stochastic resonance in a fast bistable electronic system: a tunnel diode. We investigate the phenomenon in a higher frequency regime than that studied in previous experiments. Detailed measurements of the output signal are reported for two values of the frequency of the periodic signal: ${\mathit{f}}_{\mathit{s}}$=1 kHz and ${\mathit{f}}_{\mathit{s}}$=10 kHz. We observe, in one case (${\mathit{f}}_{\mathit{s}}$=1 kHz), a nonmonotonic behavior characterized by a sharp dip in the output noise level measured at the frequency of the driving signal.
Classification and Operating Principles of Nanodevices
2017
The chapter presents and explains the classification of sensors in accordance with their physicochemical principles of functioning, as well as the types of recognition. Several prototypes of physical, chemical and biosensors based on polar molecular compounds such as indandione, fluorene and carbazole derivatives are described from the point of view of their structure and energy. One of the most important applications of nanosensitive materials is realized in the class of memory nanodevices. The realization of bistability in molecular or layered derivatives is usually carried out through processes based on tautomers and conformers, as well as phase transition processes. Typical examples of …
Photophysical Properties of Discotic Dibenzopyrenes
1997
Abstract The photophysical properties of three discogenic dibenzopyrenes substituted by eight pentyloxy (O5DPB), heptyloxy (O7DBPP) or decyloxy (O10DBP) side chains are studied in solution and thin films. It is shown that the absorption and fluorescence spectra of the columnar mesophases are clearly distinguishable from those of the corresponding crystalline phases, allowing the study of phase transitions. Thus, it is found that the shorter the lateral chain length, the slower the crystallisation process. For O5DBP, the supercooled mesophase is stable over a period of at least one year; it crystallises after cooling below the glassy transition. Such a behaviour gives rise to temperature con…
Thermochromic Meltable Materials with Reverse Spin Transition Controlled by Chemical Design
2020
International audience; We report a series of meltable FeII complexes, which, depending on the length of aliphatic chains, display abrupt forward low‐spin to high‐spin transition or unprecedented melting‐triggered reverse high‐spin to low‐spin transition on temperature rise. The reverse spin transition is perfectly reproducible on thermal cycling and the obtained materials are easily processable in the form of thin film owing to their soft‐matter nature. We found that the discovered approach represents a potentially generalizable new avenue to control both the location in temperature and the direction of the spin transition in meltable compounds.
Cooperative phenomena and light-induced bistability in iron(II) spin-crossover compounds
1999
In iron(II) spin-crossover compounds, the transition from the 1A1 low-spin state at low temperatures to the 5T2 high-spin state at elevated temperatures is accompanied by a large increase in metal-ligand bond lengths. The resulting elastic interactions may be pictured as an internal pressure which is proportional to the concentration of the low-spin species. Because pressure stabilises the low-spin state relative to the high-spin state this results in a positive feedback. Thermal transition curves in neat iron(II) spin-crossover compounds are thus invariable much steeper than in diluted mixed crystals, and the high-spin→low-spin relaxation following the light-induced population of the high-…
Clathration of Five-Membered Aromatic Rings in the Bimetallic Spin Crossover Metal–Organic Framework [Fe(TPT)2/3{MI(CN)2}2]·G (MI = Ag, Au)
2014
Six clathrate compounds of the three-dimensional spin crossover metal−organic framework formulated [Fe(TPT)2/3{MI (CN)2}2]· nG, where TPT is 2,4,6-tris(4-pyridyl)-1,3,5-triazine, MI = Ag or Au and G represent the guest molecules furan, pyrrole and thiophene, were synthesized using slow diffusion techniques. The clathrate compounds were characterized by single-crystal X-ray diffraction at 120 and 300 K, thermogravimetric analysis and thermal dependence of the magnetic susceptibility. All compounds crystallize in the R3̅ m trigonal space group. The FeII defines a unique [FeN6] crystallographic site with the equatorial positions occupied by four dicyanometallate ligands while the axial positio…
Bistable phase locking of a nonlinear optical cavity via rocking: Transmuting vortices into phase patterns.
2006
We report experimental observation of the conversion of a phase-invariant nonlinear system into a phase-locked one via the mechanism of rocking [G. J. de Valcarcel and K. Staliunas, Phys. Rev. E 67, 026604 (2003)]. This conversion results in that vortices of the phase-invariant system are being replaced by phase patterns such as domain walls. The experiment is carried out on a photorefractive oscillator in two-wave mixing configuration.A model for the experimental device is given that reproduces the observed behavior.