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1
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A Model of Optical Bistability and Polarisation Evolution in Birefringent χ^{(2)} Nonlinear Media

100%
Jęda W., Zagórski A.
Acta Physica Polonica A
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1999
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vol. 96
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issue 3-4
373-381
EN
We present a model calculation of optical bistability and polarisation evolution in optically birefringent media based on the interaction of three waves. Second-order optical nonlinearity (described by the third rank susceptibility tensor) is assumed to be dominant. A bistable light transmission is analysed in terms of standard Fabry-Perot model of feedback, and is a direct consequence of the results obtained for a semi-infinite medium. A second effect considered in the paper is evolution of polarisation state of the waves involved in these processes. We derived a closed formula for intensity-dependent refractive index, which corresponds to that used in the case of third-order nonlinear media. As a result, we calculated both intensity and Stokes parameters of transmitted light.
2
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Optical Properties of Nonlinear Periodic Structures

100%
Malcuit M. S., Herbert C. J.
Acta Physica Polonica A
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1994
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vol. 86
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issue 1
127-133
EN
The optical properties of nonlinear colloidal crystals in a distributed feedback configuration have been studied experimentally. Optical switching and bistability, optical limiting, and temporal instabilities have been observed in the transmission of these structures. The results of these experiments are compared to the theoretical predictions for the transmission properties of nonlinear periodic structures.
3
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Asymmetric Directional Coupler Controlled by Photorefractive Grating

100%
Weinert-Rączka E., Iwanow R.
Acta Physica Polonica A
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1999
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vol. 95
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issue 5
813-820
EN
An asymmetric three channel directional coupler with a thin photorefractive grating as an all-optical switching and wavelength demultiplexing element with memory is analysed.
4
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Observation of Optical Bistability in Cholesteric Liquid Crystals

100%
Pura B., Gronowska I., Petykiewicz J.
Acta Physica Polonica A
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1997
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vol. 92
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issue 3
527-533
EN
In the paper, some experimental and theoretical results concerning optical bistability in cholesteric liquid crystals are presented. A strong primary laser beam interacted nonlinearly with the material and influenced a second (probe) beam in such a way that its transmitted part exhibited a bistable dependence on the intensity of the first beam. It was observed that such a character may be attributed to the intensity of the outgoing probe wave. The obtained results reflect the symmetry of the sample and are interpreted as second order nonlinearity effects.
5
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Multiple Quantum Well Directional Coupler with Photorefractive Grating

100%
Weinert-Rączka E., Iwanow R.
Acta Physica Polonica A
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2001
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vol. 99
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issue 1
175-181
EN
We analyse an asymmetric directional coupler with a thin photorefractive grating as a switching and demultiplexing element with memory. The grating is induced by two external beams interfering in the structure of AlGaAs/GaAs multiple quantum wells with an electric field applied along the quantum well planes.
6
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Photorefractive Grating in Multiple Quantum Well Planar Waveguide

100%
Weinert-Rączka E., Wichtowski M., Ziółkowski A., Staroń G.
Acta Physica Polonica A
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2003
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vol. 103
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issue 2-3
229-237
EN
A photorefractive grating in a slab waveguide based on a semi-insulating AlGaAs/GaAs multiple quantum well structure with an electric field applied along the quantum well planes as an optically controlled, frequency selective mode coupling element with memory is analysed.
7
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Photorefractive Multiple Quantum Well Waveguide as a Bragg Reflector

100%
Wichtowski M., Weinert-Rączka E.
Acta Physica Polonica A
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2003
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vol. 103
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issue 2-3
239-248
EN
An interaction between the signal wave propagating in a planar waveguide and a photorefractive grating is analysed. The waveguide contains an AlGaAs/GaAs multiple quantum well guiding layer biased with an external electric field applied along the wells plane. The grating is formed by two external beams interfering in the multiple quantum well layer. The dependence of the steady-state grating properties on the external waves parameters and applied electric field intensity is presented. Possible application of the grating as an optically controlled Bragg reflector with memory is analysed.
8
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Optical Polarisation Bistability in χ^2 Media at Large Desynchronisation Regime

80%
Jęda W., Zagórski A.
Acta Physica Polonica A
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2004
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vol. 105
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issue 4
357-363
EN
In this work we present results of calculations concerning bistability of optical polarisation in birefringent media. Second-order optical nonlinearity is assumed to be dominant and represented by one parameter. In our model the second-harmonic generation regime is assumed. Light transmission is analysed in terms of standard Fabry-Perot model of feedback. We derived formulas for the Stokes parameters describing the polarisation state. Numerical results showed that three parameters may exhibit bistable behaviour. This creates new possibilities for optical switching.
9
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Energy Localization Through Bragg Gratings in Quadratic Media for Second Harmonic Generation

80%
Conti C., Assanto G., Trillo S.
Acta Physica Polonica A
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1999
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vol. 95
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issue 5
719-726
EN
In a waveguide for second-harmonic generation, a linear corrugation able to couple counterpropagating waves at the second-harmonic and/or at the fundamental frequency can induce localization effects through the formation of gap-simultons, i.e. bi-color gap-solitons. These can move slowly or be stationary, collide and merge. All-optical memories are envisaged.
10
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Optical Bistability Induced by Additive Colored Noise in the Exciton-Biexciton System

80%
Gonţia I., Rotaru A.
Acta Physica Polonica A
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1995
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vol. 87
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issue 6
911-917
EN
This paper predicts optical bimodality induced by external additive noise with a finite bandwidth, in the exciton-biexciton system.
11
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Optical Bistability Due to Photo-Induced Charge Transfer in a Type-II GaAs/AlAs Quantum Well

80%
Teissier R., Planel R., Mollot F.
Acta Physica Polonica A
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1992
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vol. 82
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issue 4
656-659
EN
We present a bistability of low temperature photoluminescence in a n-i-n type-II GaAs/AlAs quantum heterostructure. Spectral analysis and electrical measurements indicate that the two states correspond to hole accumulation in different layers. The transition occurs with the alignment of electronic Γ and X states due to optical pumping, and no external voltage bias is needed.
12
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Enhanced Electro-Optic Modulation Performance in Optical Buffers by Slowing Light in Optimized Photonic Crystal Slab Structures

80%
Bagci F., Akaoglu B.
Acta Physica Polonica A
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2014
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vol. 125
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issue 2
611-614
EN
Slow light holds the key to advanced optical buffering and time-domain optical signal processing technologies. Photonic crystal based optical buffers are particularly attractive due to their nanoscale size, room temperature operation, and enhanced field dependent nonlinear response associated with the presence of slow light. In this study, the slow light and electro-optic modulation characteristics of a line-defect Si photonic crystal slab with triangular arrangement of holes filled with an electro-optic polymer (n = 1.6) are investigated by three-dimensional plane-wave expansion and finite-difference time-domain methods. The first rows adjacent to the line-defect are shifted gradually in the direction of light propagation and a slow light region with a high group index below the light-line is obtained for a shifting amount between 0.22a and 0.27a. For the photonic crystal configuration with 0.22a shifted rows, under modulated voltage change, the average group index is found to be decreasing with an increase in the bandwidth. The results show that the low group velocity supports a large delay time in a small modulated voltage variation. A linear change of group index with modulated voltage is obtained and the modulation sensitivity of central wavelength is obtained as 9.45 nm/V for a delay line length of 0.5 mm. Almost the same buffer capacity and bit length are found which provides the control of delay time flexibly while keeping the buffer capacity and the bit length almost unchanged.
13
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Dependence of Modulation Bandwidth on Size of Optical Injection Locked Semiconductor Ring Laser

80%
Memon M., Fathallah H.
Acta Physica Polonica A
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2014
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vol. 125
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issue 2
462-464
EN
It has been successfully investigated for the first time that strength of optical injection locking also depends on the size of semiconductor ring laser. Theoretical study for frequency response of optical injection locking semiconductor ring laser in the master slave configuration using direct, amplitude and phase modulation of master laser is discussed. In the unidirectional regime the locking range of semiconductor ring laser becomes wider when semiconductor ring laser with smaller size is used. Simulation results predict an incredible enhancement in the modulation bandwidth (> 500 GHz) of the slave semiconductor ring laser when used with smaller laser cavity length (50 μm) in the stable unidirectional regime.
14
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Noise Response and Stability in Injection Locked Semiconductor Ring Laser

80%
Memon M., Fathallah H.
Acta Physica Polonica A
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2014
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vol. 125
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issue 2
454-455
EN
Stability and effects of optical injection locking in semiconductor ring laser is modeled in detail. It is verified that the injection locking in slave semiconductor ring laser depends on detuning frequency and external optical injection ratio between the master laser and the slave semiconductor ring laser. The stability of injection was locked using the resonance frequency and damping factor. The parasitic phase modulation response due to amplitude modulation (chirp response) is derived and simulated. Similarly parasitic amplitude modulation due to phase modulation response is also investigated.
15
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Fast Speed Semiconductor Ring Lasers Using Optical Injection Locking

70%
Memon M., Fathallah H., Yu S.
Acta Physica Polonica A
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2013
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vol. 123
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issue 2
180-182
EN
Theoretical study for frequency response and modulation bandwidth of slave semiconductor ring laser in the master-slave configuration using optical injection locking has been investigated. Equations for frequency response of optical injection locking-semiconductor ring laser to the direct modulation, amplitude modulation of master laser, respectively, are derived and simulated. Enhancement in the modulation bandwidth of >100 GHz is reported between negative to positive detuning frequency and increasing injection power ratio.
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