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1.
We present an optofluidic nonlinear waveguide array that is fabricated by selectively filling several strands of a photonic crystal fiber with the liquid CCl(4), which exhibits a large focusing ultrafast Kerr nonlinearity. We demonstrate a power dependent formation of a spatial soliton in this novel optofluidic device. The large thermo-optical effect of liquids enables us to control the characteristics of the spatial soliton formation in these nonlinear structures. This opens the road toward flexible designs and the realization of a new class of optofluidic devices with complex nonlinear landscapes and novel effects.  相似文献   

2.
We showed that the application of a soliton in a nonlinear coupler does not show a better switching performance than a Gaussian pulse, unlike what the existing theory expected. Like the Gaussian pulse, a soliton could also suffer distortion, broadening, or narrowing in a nonlinear directional coupler. In addition, by using a new normalized format the linearly coupled nonlinear Schrödinger equations were investigated. For the first time, we found that both the coupling behavior and the switching performance of pulses in a nonlinear coupler depend on the product of the coupling coefficient and the dispersion length. We also showed that for a given nonlinear coupler with a Gaussian-like or soliton-like pulse input, switching performance and whether a pulse breaks up or not mainly depend on the input pulse width, not the pulse shape. PACS 42.65.Tg; 42.65.Wi; 42.81.Qb  相似文献   

3.
三芯非线性光纤耦合器中的短脉冲光开关   总被引:5,自引:0,他引:5       下载免费PDF全文
利用变分法研究三芯非线性光纤耦合器中的短脉冲光开关,解析分析线性三耦合非线性Schr?dinger方程的结果与数值模拟符合得很好.并且得到在非线性光纤耦合器中孤子的耦合长度和开关阈值,与连续波情况和两芯光纤耦合器的结果不同. 关键词: 光纤耦合器 光开关 耦合长度 开关阈值  相似文献   

4.
5.
A numerical investigation of nonlinear switching in plasmonic directional couplers made of two dielectric slab waveguides with metallic claddings is presented. We assume Kerr-nonlinear dielectric and study the influence of geometrical parameters, metallic losses, and metal nonlinearities on coupler characteristics. We observe a general trade-off between losses and nonlinearity levels required for the switching operation. Underlying physical mechanisms that affect the coupler performance are discussed. The obtained results can be useful in design and optimization of the nonlinear plasmonic couplers.  相似文献   

6.
The nonlinear switching characteristics of fused fiber directional couplers were studied experimentally. By using femtosecond laser pulses with pulse width of 100 fs and wavelength of about 1550 nm from a system of Ti:sapphire laser and optical parametric amplifier (OPA), the nonlinear switching properties of a null coupler and a 100% coupler were measured. The experimental results were coincident with the simulations based on nonlinear propagation equations in fiber by using super-mode theory. Nonlinear loss in fiber was also measured to get the injected power at the coupler. After deducting the nonlinear loss and input efficiency, the nonlinear switching critical peak powers for a 100% and a null fused couplers were calculated to be 9410 and 9440 W, respectively. The nonlinear loss parameter PN in an expression of αNL = αP/PN was obtained to be PN = 0.23 W.  相似文献   

7.
This paper reports a detailed numerical study of soliton switching in a high as well as low birefringent nonlinear coupler. It is shown that by controlling the polarization angle one can have nearly 100% transmission with excellent switching characteristics. It is shown that soliton remains stable during its propagation inside the coupler. However it is observed that high birefringent coupler exhibits relatively better soliton stability. We show that the coupler could be used as a soliton switch even at an input peak power less than the critical power, the power at which 50-50 power sharing takes place between the two cores, just by a judicious choice of the polarization angle.  相似文献   

8.
Ha S  Sukhorukov AA  Kivshar YS 《Optics letters》2007,32(11):1429-1431
We study propagation and switching of slow-light pulses in nonlinear couplers with phase-shifted Bragg gratings. We demonstrate that power-controlled nonlinear self-action of light can be used to compensate for dispersion-induced broadening of pulses through the formation of gap solitons, to control pulse switching in the coupler, and to tune the propagation velocity.  相似文献   

9.
We propose the use of KTP-based waveguides for all-optical switching. The passing of subnanosecond light pulses through the Rb:KTP nonlinear directional coupler is investigated. The nonlinear switching of 40% of light power from the one channel to another is observed at 5 kW input power.  相似文献   

10.
The Zeno effect is investigated for soliton type pulses in a nonlinear directional coupler with dissipation. The effect consists in increase of the coupler transparency with increase of the dissipative losses in one of the arms. It is shown that localized dissipation can lead to switching of solitons between the arms. Power losses accompanying the switching can be fully compensated by using a combination of dissipative and active (in particular, parity-time-symmetric) segments.  相似文献   

11.
We have investigated the switching performance of a gained (nonlinear directional coupler) NLDC switch in the presence of both 2nd and 4th order gain nonlinearities. In this system, we have achieved a nearly complete pulse switching at half beat length of the coupler which implies about 40% reduction in the switching length as compared to the switching length reported in Trillo et al. (1988). We have shown that at the half beat length the output energy of each branch is equal to that of the input energy and hence the gained NLDC switches have ability to be cascaded. Our initial investigations reveal that this gained NLDC switch has remarkable performance and potential to be used in ultra-fast optical communication systems.  相似文献   

12.
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   

13.
Taking advantage of the nonlinear phase-shift obtainable via up- and down-conversion of a beam to and from its second- harmonic, an efficient all-optical switch can be realized adopting the standard directional coupler configuration with strong nonlinear asymmetry. Using coupled-mode theory we numerically demonstrate power switching in a half-beat length coupler with remarkable functional characteristics in a wide range of parameters.  相似文献   

14.
A numerical study of the all-optical switching properties of an active nonlinear directional coupler is presented. The switching power is reduced for both CW and soliton inputs because of the gain. The switching properties of the coupler are enhanced for solitons, which switch nearly completely. For ultrashort pulses, the effects of the bandwidth of the gain medium are considered by using a general form for the gain band. The gain spectrum of erbium is also considered as a specific example.  相似文献   

15.
研究了高斯—常数—高斯平滑连接的复合型变耦合系数定向耦合器的开关特性曲线。研究了耦合器各分段长度对开关曲线的影响。数值模拟发现,耦合器各组成部分的参量对耦合器开关曲线尾部的振荡及开关功率的大小均有影响,且呈现出一定的规律性。高斯型波导部分的相对长度以及直波导部分所占份额共同决定了耦合器开关曲线尾部的振荡大小,且开关曲线的振荡与耦合函数的傅里叶变换的振荡密切相关。  相似文献   

16.
Xiujun He  Kang Xie  Huajun Yang 《Optik》2012,123(24):2247-2249
With study for switching characteristics and output coupling ratio of fiber nonlinear directional couplers (NLDC), we found that the influence elements on the switching characteristics and output coupling ratio had gain of core 1 and 2, nonlinear coefficient of those, the input power and width of input soliton. We also found numerically that switching efficiencies were improved by controlling gain of core 1, different output coupling ratio would be obtained by controlling gain of core 1 or 2. And we can change the gain by changing pump power of the optical fiber amplifiers. From this, we also made fiber coupler which output coupling ratio was changeable.  相似文献   

17.
A detailed numerical study of soliton switching in a nonlinear directional coupler with saturating nonlinearity is carried out. All commonly used models have been studied. Relevant physical characteristics for switching have been determined, compared and discussed.  相似文献   

18.
Dark soliton switching in a nonlinear directional coupler in the presence of intermodal dispersion, cross-phase modulation (CPM), third-order dispersion, Raman effect, and self-steepening effect is reported for the first time. It is shown that, with the exception of CPM, all of the other perturbative effects have almost no effect on the switching characteristics of the dark soliton switch, which is an improvement over the corresponding bright soliton switch. Although the CPM increases the critical power of dark soliton switching, the soliton pulse remains stable inside the coupler during its propagation.  相似文献   

19.
Prasanta Mandal  Swati Midda 《Optik》2011,122(20):1795-1798
Logic gates are the fundamental building blocks in any digital data processing system. Several all optical logic operations are already proposed by scientists and technologists. Here the authors proposed a new method of all optical logic operation based on nonlinear directional coupler. Effective optical switching is achieved by modifying the coupling length between the coupler waveguides by means of an optical signal.  相似文献   

20.
利用两种方法研究了高速光脉冲在具有交叉相位调制的等边三角形排列结构的非线性三芯光纤耦合器中传输和开关特性.首先利用变分原理得到三纤芯中传输转移系数随距离变化的方程,然后利用分裂步长傅里叶方法求得了光脉冲的数值解.变分法和数值模拟的结果表明:当一阶模间色散系数较小时,光脉冲仍能在三芯之间周期性耦合传输,并且表现出良好的开关特性,但是随着一阶模间色散系数的增大,脉冲耦合传输的周期性和陡峭的开关特性都遭到破坏,光脉冲在传输中发生分裂;二阶耦合色散系数和初始啁啾都能使光脉冲传输时的耦合长度变短、光脉冲在三纤芯之间 关键词: 三芯光纤耦合器 模间色散系数 耦合长度 开关阈值功率  相似文献   

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