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1.
An optical fiber grating coupler (FGC) is a fused optical fiber coupler with a tapered region in which refractive index-modulated gratings are written. In the FGC, the light with specific wavelength satisfying the Bragg condition of the grating can be dropped to one output port and other lights are transmitted to another output port when lights with various wavelengths are launched into the input port. The FGC can operate as an all-optical switch by controlling the Bragg wavelength of the grating using a third order nonlinear optical effect caused by a control light that are launched with a signal light. In this paper, an all-optical switching operation due to a third order nonlinear optical effect in an FGC is first demonstrated for a signal light with 1.55 μm-wavelength to be changed from one port of the FGC to another one by the 720 W peak of a control light from a Nd:YAG laser with 1.06 μm-wavelength. The switching efficiency obtained was 7%. It was clarified that a longer pulse length of the control light compared to the grating length is required to obtain a large Bragg wavelength shift for the switching. It was also clarified that the Bragg wavelength shift is caused by a third order nonlinear effect and a photothermal effect. A contribution of the photothermal effect was estimated. We also estimated the switching efficiency for pump power in the FGC switch.  相似文献   

2.
We demonstrate optical bistability (OB) in a defect slab doped V-type four-level InGaN/GaN quantum dot nanostructure in the negative refraction frequency band. It has been shown that the OB behavior of such a quantum dot nanostructure system can be controlled by the amplitude of the driving fields and a new parameter for controlling the OB behavior as thickness of the slab medium in the negative refraction band. Meanwhile, we show that the negative refraction frequency band can be controlled by tuning electric permittivity and magnetic permeability by the amplitude of the driving fields and electron concentration in the defect slab doped. Under the numerical simulations, due to the effect of quantum coherence and interference, it is possible to switch bistability by adjusting the optimal conditions in the negative refraction frequency band, which is more practical in all-optical switching or coding elements, and technology based nanoscale devices.  相似文献   

3.
We propose a novel all-optical controllable switch using photonic crystal cavity. For doing this work, the dipole induced transparency phenomenon realized through interaction of light with multilevel nanocrystals is used. Multilevel nanocrystals are doped to photonic crystal rods. Using the proposed structure and applying the control field, the absorbing medium converts to transparent one and switching operation is obtained. Analytical relation for evaluation of the proposed device considering quantum optical effects is presented and studied by investigation of effects of parameters on switching characteristics. We show that high quality all-optical switching operation can be obtained.  相似文献   

4.
Low-power all-optical bistable liquid crystal (LC) devices are reported in which surface plasmons propagate along a metallic grating. The threshold switching illumination was 1.4 mW/mm2 in the device with the twisted-nematic LC cell. This is a lower value than for all-optical bistable devices reported previously. This low-power bistability device can be used in two-dimensional optical memories or spatial light modulators.  相似文献   

5.
利用腔内四能级原子相干效应实现全光学信号存储   总被引:1,自引:0,他引:1  
王海  常宏  武海斌  谢常德 《物理》2005,34(4):250-253
在光学腔与四能级原子组成的非线性光学双稳系统中,利用调谐于不同能级附近的控制信号光脉冲可以使光学腔模产生“IT”或“负”的非线性相移,从而实现了光学双稳迟滞曲线的受控移动及双稳“高态”与“低态”之间的可控跃变,基于上述效应,完成了光学信号的全光存储与腔输出状态的低功率控制开关.这一结果为全光及量子信息处理提供了新的可供利用的物理机制.  相似文献   

6.
The dispersive-absorptive optical properties of a weak probe field are investigated based on quantum coherence and interference in a Landau-quantized graphene structure. It is found that an enhanced refractive index with vanishing absorption can be obtained in this structure through proper adjusting the controlling parameters of the system. The switching between superluminal and subluminal light propagation is also discussed. Our scheme can be employed in real experiments to develop new types of nanoelectronic devices for realizing all-optical switching process and can have practical application in dispersion compensation and solid-state quantum communication.  相似文献   

7.
Yang ZS  Kwong NH  Binder R  Smirl AL 《Optics letters》2005,30(20):2790-2792
We describe a reflection scheme that allows Bragg-spaced semiconductor quantum wells to be used to trap, store, and release light. We study the temporal and spectral distortion of delayed light pulses and show that this geometry allows multibit delays and offers a high degree of distortion compensation.  相似文献   

8.
《Physics letters. A》2019,383(19):2248-2254
We analyze the dynamical behavior of all-optical switching and memory based on tunable optical bistability in a three-level Λ-type atomic system driven by a probe field circulating in an optical ring cavity, a coherent coupling field and an incoherent pump field outside cavity. Owing to the incoherent pump process, the absorption and Kerr nonlinearity near the atomic resonance change dramatically as a result of varied population distribution and atomic coherence, and then the switch-up and switch-down thresholds, as well as the width (or area) of bistable curve, can be manipulated effectively. By tuning the intensity of either coherent coupling field or incoherent pump field, we can make the system output flip between the lower and upper branches of different bistable hysteresis loops while the cavity input keeps to a constant value. Accordingly, all-optical switching and memory can be implemented via dynamical control of the bistable behavior under the assistance of incoherent pump. The proposed scheme can find potential applications in all-optical communication and computation.  相似文献   

9.
Chinmoy Taraphdar 《Optik》2011,122(1):33-36
In this paper, for the first time to our knowledge, we propose and describe a novel design of single circuit capable of generating all the possible 27 logic functions for single input ternary (3-valued) logic system in all-optical domain. Here the different logical states have been represented by different polarized state of light. Terahertz optical asymmetric demultiplexer (TOAD) based interferometric switch plays a significant role as ultra-fast all-optical switching device. Proposed all-optical circuit is numerically investigated and simulated.  相似文献   

10.
Nonlinear photonic crystals made from polystyrene materials that have Kerr nonlinearity can exhibit ultrafast optical switching when the samples are pumped by ultrashort optical pulses with high intensity due to the change of the refractive index of polystyrene and subsequent shift of the band gap edge or defect state resonant frequency. Polystyrene has a large Kerr nonlinear susceptibility and almost instantaneous response to pump light, making it suitable for the realization of ultrafast optical switching with a response time as short as a few femtoseconds. In this paper, we review our experimental progress on the continual improvement of all-optical switching speed in two-dimensional and three-dimensional polystyrene nonlinear photonic crystals in the past years. Several relevant issues are discussed and analyzed, including different mechanisms for all-optical switching, preparation of nonlinear photonic crystal samples by means of microfabrication and self-assembly techniques, characterization of optical switching performance by means of femtosecond pump-probe technique, and different ways to lower the pump power of optical switching to facilitate practical applications in optical information processing. Finally, a brief summary and a perspective of future work are provided.  相似文献   

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