Pattern formation in a single-mirror system containing an atomic vapor as the nonlinear medium is... more Pattern formation in a single-mirror system containing an atomic vapor as the nonlinear medium is discussed. It is shown in the case of sodium atoms that the properties of the medium can drastically be modified by the use of an oblique magnetic field which induces a light-shift-induced levelcrossing. The phenomena observed in the system include a transition from negative to positive hexagons and a secondary bifurcation from hexagons to ultrahexagons. When linearly or elliptically polarized light is used the pattern formation involves a decomposition of the light field into its circularly polarized components. A transition from positive to negative hexagons occurs in one polarization component, when the ellipticity of the polarization passes zero; the other component displays the opposite behavior. The transition is mediated by squares. The hexagons obtained for weakly elliptical polarization at threshold undergo a secondary bifurcation to squares if the power of the input beam is in...
Photonics North 2004: Photonic Applications in Telecommunications, Sensors, Software, and Lasers, 2004
This paper reports the design of InP-based monolithic photonic integrated circuits for performanc... more This paper reports the design of InP-based monolithic photonic integrated circuits for performance surveillance and bandwidth management in DWDM transmission systems. It is based on a building block approach, which allows a large variety of optical components to be built from a few monolithically integrable elements, by using only one-step epitaxial growth and standard semiconductor fabrication technologies. These include: (i)
Optical pattern formation in a spin-1/2 atomic system is theoretically studied in the situation o... more Optical pattern formation in a spin-1/2 atomic system is theoretically studied in the situation of interaction between the Hopf and static instabilities. Variation of the parameters of the system permits a drastic change of the ratio between the spatial wave numbers of the Hopf and the static modes. If the mode coupling satisfies spatiotemporal phase matching conditions, regular patterns in
It is demonstrated that the Hopf spatiotemporal modes can build stable resonant triads in an opti... more It is demonstrated that the Hopf spatiotemporal modes can build stable resonant triads in an optical pattern-forming system with delay. The resonant Hopf triads correspond to dissipative structures in the form of drifting patterns of rhombic, hexagonal, or rhomboidal symmetry. Multistability of different patterns is found in numerical simulations.
ABSTRACT Summary form only given. Studying of soliton like structures in nonlinear optical system... more ABSTRACT Summary form only given. Studying of soliton like structures in nonlinear optical systems gain an importance in the recent years due to the possibility of its applications in optical devices of information processing and storage. Apart from this the general interest attract structures that appear in multicomponent systems. Different components can nonlinearly interact, that leads to the arising of nontrivial spatial solitons. We theoretically investigate a system, comprising of two thin layers (with thickness less than the incident light wavelength) with a resonant nonlinearity. Layers are separated by a linear medium and irradiated from both sides by a monochromatic and spatially homogeneous light wave. It is obvious that in the case of equal incident fields, there is a symmetrical solution where all variables in both films are equal. We have shown that with increasing incident fields (symmetrical from both sides) pitchfork symmetry-breaking bifurcation takes place above some threshold. Taking into account transverse spatial perturbations we have found pattern-forming instabilities on the symmetrical and nonsymmetrical branches. We concentrate on the symmetrical branch near the pitchfork symmetry-breaking bifurcation.
ABSTRACT A theoretical investigation is reported of the interaction of light with a system of two... more ABSTRACT A theoretical investigation is reported of the interaction of light with a system of two films which contain two-level centres and whose thickness is less than the incident radiation wavelength. It is shown that when light of the same intensity is incident from both sides of the films, symmetry-breaking bifurcation is possible, i.e. the transmitted fields are different for the opposite directions. The relationship between symmetry-breaking bifurcation and optical bistability is determined. If the distance between the films represents an odd number of the optical half-wavelengths symmetry breaking occurs at a lower value of the parameter representing the interaction nonlinearity than that corresponding to the onset of bistability. The opposite is true when an even number of half-wavelengths can be fitted between the films. The supression of symmetry-breaking bifurcation is illustrated for various intensities of the incident optical field.
We report the observation of the transition between positive and negative hexagons by using optic... more We report the observation of the transition between positive and negative hexagons by using optical pattern formation in a sodium vapor cell with a feedback mirror. We show that because of a secondary instability of a developed hexagon against its spatial ultraharmonics a new pattern (ultrahexagon) appears. Pattern formation for an incident Gaussian light beam takes place in combination with
Twelvefold quasiperiodic structures are observed in an autonomous optical pattern forming system ... more Twelvefold quasiperiodic structures are observed in an autonomous optical pattern forming system with continuous rotational symmetry. These quasipatterns arise from a primary hexagonal structure. In dependence on the experimental parameters the bifurcation can be sub- or supercritical. In the supercritical case, the transition is mediated by a new kind of patterns with different amplitudes in its fundamental modes. It is
It is demonstrated experimentally and theoretically that a light-shift-induced level crossing in ... more It is demonstrated experimentally and theoretically that a light-shift-induced level crossing in an oblique magnetic field results in a nonmonotonous dependency of the transmission of a sodium vapor cell on the input power. If feedback by a single plane mirror is added, bistability of the transmission and of the beam profile (resonatorless transverse optical bistability) is observed. The origin of
Journal of Optics B: Quantum and Semiclassical Optics, 2000
ABSTRACT A system comprising two nonlinear thin films irradiated from both sides by monochromatic... more ABSTRACT A system comprising two nonlinear thin films irradiated from both sides by monochromatic light is considered. It is shown that interplay of a subcritical pitchfork symmetry-breaking bifurcation and a pattern-forming instability gives rise to the formation of symmetry-breaking soliton-like structures below the onset of the above instabilities.
Journal of Optics B: Quantum and Semiclassical Optics, 2001
ABSTRACT The use of polarization degrees of freedom in optimizing the conditions for optical patt... more ABSTRACT The use of polarization degrees of freedom in optimizing the conditions for optical pattern formation is investigated by discussing the particular example of single-mirror feedback systems. It is demonstrated that in a quasi-scalar saturable medium pattern formation may be completely suppressed by the interplay of saturation and diffusion. This effect takes place for the optical pumping nonlinearity between Zeeman ground states in alkaline vapour cells. It is shown that these limitations can be circumvented by introducing additional polarization components either in the input beam or in the feedback beam. The latter is achieved by introducing polarization-changing elements such as a quarter-wave plate in the feedback loop. In the optimized scheme, pattern formation is obtained with rather low thresholds. Thus, investigations with a rather high aspect ratio and far beyond threshold become feasible.
Journal of Optics B: Quantum and Semiclassical Optics, 1999
... Of course, the question of the stability, respectively instability, of binary systems does no... more ... Of course, the question of the stability, respectively instability, of binary systems does not only arise in nonlinear optics. ... The precise nature of the resultant structure in the optical system remains to be investigated since our analysis can ... Modulational instability and beam splitting ...
Pattern formation in a single-mirror system containing an atomic vapor as the nonlinear medium is... more Pattern formation in a single-mirror system containing an atomic vapor as the nonlinear medium is discussed. It is shown in the case of sodium atoms that the properties of the medium can drastically be modified by the use of an oblique magnetic field which induces a light-shift-induced levelcrossing. The phenomena observed in the system include a transition from negative to positive hexagons and a secondary bifurcation from hexagons to ultrahexagons. When linearly or elliptically polarized light is used the pattern formation involves a decomposition of the light field into its circularly polarized components. A transition from positive to negative hexagons occurs in one polarization component, when the ellipticity of the polarization passes zero; the other component displays the opposite behavior. The transition is mediated by squares. The hexagons obtained for weakly elliptical polarization at threshold undergo a secondary bifurcation to squares if the power of the input beam is in...
Photonics North 2004: Photonic Applications in Telecommunications, Sensors, Software, and Lasers, 2004
This paper reports the design of InP-based monolithic photonic integrated circuits for performanc... more This paper reports the design of InP-based monolithic photonic integrated circuits for performance surveillance and bandwidth management in DWDM transmission systems. It is based on a building block approach, which allows a large variety of optical components to be built from a few monolithically integrable elements, by using only one-step epitaxial growth and standard semiconductor fabrication technologies. These include: (i)
Optical pattern formation in a spin-1/2 atomic system is theoretically studied in the situation o... more Optical pattern formation in a spin-1/2 atomic system is theoretically studied in the situation of interaction between the Hopf and static instabilities. Variation of the parameters of the system permits a drastic change of the ratio between the spatial wave numbers of the Hopf and the static modes. If the mode coupling satisfies spatiotemporal phase matching conditions, regular patterns in
It is demonstrated that the Hopf spatiotemporal modes can build stable resonant triads in an opti... more It is demonstrated that the Hopf spatiotemporal modes can build stable resonant triads in an optical pattern-forming system with delay. The resonant Hopf triads correspond to dissipative structures in the form of drifting patterns of rhombic, hexagonal, or rhomboidal symmetry. Multistability of different patterns is found in numerical simulations.
ABSTRACT Summary form only given. Studying of soliton like structures in nonlinear optical system... more ABSTRACT Summary form only given. Studying of soliton like structures in nonlinear optical systems gain an importance in the recent years due to the possibility of its applications in optical devices of information processing and storage. Apart from this the general interest attract structures that appear in multicomponent systems. Different components can nonlinearly interact, that leads to the arising of nontrivial spatial solitons. We theoretically investigate a system, comprising of two thin layers (with thickness less than the incident light wavelength) with a resonant nonlinearity. Layers are separated by a linear medium and irradiated from both sides by a monochromatic and spatially homogeneous light wave. It is obvious that in the case of equal incident fields, there is a symmetrical solution where all variables in both films are equal. We have shown that with increasing incident fields (symmetrical from both sides) pitchfork symmetry-breaking bifurcation takes place above some threshold. Taking into account transverse spatial perturbations we have found pattern-forming instabilities on the symmetrical and nonsymmetrical branches. We concentrate on the symmetrical branch near the pitchfork symmetry-breaking bifurcation.
ABSTRACT A theoretical investigation is reported of the interaction of light with a system of two... more ABSTRACT A theoretical investigation is reported of the interaction of light with a system of two films which contain two-level centres and whose thickness is less than the incident radiation wavelength. It is shown that when light of the same intensity is incident from both sides of the films, symmetry-breaking bifurcation is possible, i.e. the transmitted fields are different for the opposite directions. The relationship between symmetry-breaking bifurcation and optical bistability is determined. If the distance between the films represents an odd number of the optical half-wavelengths symmetry breaking occurs at a lower value of the parameter representing the interaction nonlinearity than that corresponding to the onset of bistability. The opposite is true when an even number of half-wavelengths can be fitted between the films. The supression of symmetry-breaking bifurcation is illustrated for various intensities of the incident optical field.
We report the observation of the transition between positive and negative hexagons by using optic... more We report the observation of the transition between positive and negative hexagons by using optical pattern formation in a sodium vapor cell with a feedback mirror. We show that because of a secondary instability of a developed hexagon against its spatial ultraharmonics a new pattern (ultrahexagon) appears. Pattern formation for an incident Gaussian light beam takes place in combination with
Twelvefold quasiperiodic structures are observed in an autonomous optical pattern forming system ... more Twelvefold quasiperiodic structures are observed in an autonomous optical pattern forming system with continuous rotational symmetry. These quasipatterns arise from a primary hexagonal structure. In dependence on the experimental parameters the bifurcation can be sub- or supercritical. In the supercritical case, the transition is mediated by a new kind of patterns with different amplitudes in its fundamental modes. It is
It is demonstrated experimentally and theoretically that a light-shift-induced level crossing in ... more It is demonstrated experimentally and theoretically that a light-shift-induced level crossing in an oblique magnetic field results in a nonmonotonous dependency of the transmission of a sodium vapor cell on the input power. If feedback by a single plane mirror is added, bistability of the transmission and of the beam profile (resonatorless transverse optical bistability) is observed. The origin of
Journal of Optics B: Quantum and Semiclassical Optics, 2000
ABSTRACT A system comprising two nonlinear thin films irradiated from both sides by monochromatic... more ABSTRACT A system comprising two nonlinear thin films irradiated from both sides by monochromatic light is considered. It is shown that interplay of a subcritical pitchfork symmetry-breaking bifurcation and a pattern-forming instability gives rise to the formation of symmetry-breaking soliton-like structures below the onset of the above instabilities.
Journal of Optics B: Quantum and Semiclassical Optics, 2001
ABSTRACT The use of polarization degrees of freedom in optimizing the conditions for optical patt... more ABSTRACT The use of polarization degrees of freedom in optimizing the conditions for optical pattern formation is investigated by discussing the particular example of single-mirror feedback systems. It is demonstrated that in a quasi-scalar saturable medium pattern formation may be completely suppressed by the interplay of saturation and diffusion. This effect takes place for the optical pumping nonlinearity between Zeeman ground states in alkaline vapour cells. It is shown that these limitations can be circumvented by introducing additional polarization components either in the input beam or in the feedback beam. The latter is achieved by introducing polarization-changing elements such as a quarter-wave plate in the feedback loop. In the optimized scheme, pattern formation is obtained with rather low thresholds. Thus, investigations with a rather high aspect ratio and far beyond threshold become feasible.
Journal of Optics B: Quantum and Semiclassical Optics, 1999
... Of course, the question of the stability, respectively instability, of binary systems does no... more ... Of course, the question of the stability, respectively instability, of binary systems does not only arise in nonlinear optics. ... The precise nature of the resultant structure in the optical system remains to be investigated since our analysis can ... Modulational instability and beam splitting ...
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