Analysis of novel optical properties of subwavelength double-layers metallic grating

We present a theoretical Fabry–Pèrot-Like model for the novel optical response of the subwavlength double-layers metal grating. The Fabry–Pèrot-Like resonance phenomenon has been found in this structure, and the complex cavities model is carried out for the interpretation of the resonant frequency shift due to the SPPs’ effect for the TM mode. The SPPs exist or not for TE and TM mode lead to different resonance frequency. We conclude that the reflection coefficient minimum corresponds to the condition satisfying the Fabry–Pèrot-Like resonance situation no matter for TE or TM mode. PACS 42.79.Dj; 71.36.+c; 73.20.Mf; 78.66.Bz     

All-optical switching and nonlinear optical properties of HBT in ethanol solution

This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He--Ne signal beam at 632.8 nm with 2-(2^\prime -hydroxyphenyl)benzothiazole (HBT) in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer (ESIPT) effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.     

Strong modification of the nonlinear optical response of metallic subwavelength hole arrays

The influence of hole shape on the nonlinear optical properties of metallic subwavelength hole arrays is investigated. It is found that the amount of second harmonics generated can be enhanced by changing the hole shape. In part this increase is a direct result of the effect of hole shape on the linear transmission properties. Remarkably, in addition to enhancements that follow directly from the linear properties of the array, we find a hot hole shape. For rectangular holes the effective nonlinear response is enhanced by more than 1 order of magnitude for one particular aspect ratio. This enhancement can be attributed to slow propagation of the fundamental wavelength through the holes which occurs close to the hole cutoff.     

All-optical switching in quadratically nonlinear waveguide arrays

We demonstrate a scheme for efficient switching and routing of low-power signals in waveguide arrays with second-order nonlinearity. With control beams the signal can be switched to different output positions and can be simultaneously converted to another wavelength with low cross talk.     

光交换节点中的全光再生技术研究

比较了光交换节点中几种全光再生技术方案的优缺点,重点描述光纤参量振荡器的时钟提取实验和基于磁光四波混频的光门整形技术。实验揭示了光纤参量振荡器闲频光反馈控制方法的工作原理,并提取出稳定的高质量时钟信号。仿真比较了4种四波混频光门再生方案的功率转移特性,开展了磁光四波混频再生实验。研究表明:通过对高非线性光纤加载180 Gs直流磁场,可使光接收机灵敏度进一步提升2 dB。最后指出了全光再生技术的多信道、集成化发展趋势。     

All-optical switching in an antiwaveguiding structure

We consider a multichannel optical switch based on a combination of a nonlinear antiwaveguide and several parallel waveguides. The switching is controlled by a perpendicular laser beam focused on the surface of the device. We perform numerical simulations and consider in detail the 1 N switching in such a structure.     

All-optical switching of the transmission of electromagnetic radiation through subwavelength apertures

Unprecedented optical control of the surface plasmon polariton assisted transmission of terahertz radiation through subwavelength apertures is rendered possible by carrier-induced changes to the dielectric properties of a semiconductor grating. Although the study presented is static, the extension of our approach to dynamic switching and tuning is deemed straightforward, opening the way for the realization of ultrafast surface plasmon based devices.     

All-optical switching at the Fano resonances in subwavelength gratings with very narrow slits

We theoretically discuss all-optical switching at the Fano resonances of subwavelength gratings made of a chalcogenide glass (As(2)S(3)). Particular attention is devoted to the case in which the grating possesses extremely narrow slits (channels ranging from a～10 nm to a～40 nm). The remarkable local field enhancement available in these situations conspires to yield low-threshold switching intensities (~50 MW/cm(2)) at telecommunication wavelengths for extremely thin (d～200 nm) gratings when a realistic value of the As(2)S(3) cubic nonlinearity is used.     

All-optical wavelength converters for optical switching applications

We present the latest results about all-optical wavelength conversion obtained within the European Union—funded RACE ATMOS project. In particular, solutions based on carrier depletion in Distributed Brag Reflector lasers have reached penalty-free polarization-insensitive operation at up to 2.5 Gbit/s, while solutions based on Semiconductor Optical Amplifiers (SOAS) under cross-gain modulation have been demonstrated at more than 20 Gbit/s. The study of cross-phase modulation in SOAs has also been performed, leading to the monolithic integration of SOAs within an interferometer, according to structures proposed by the project. Penalty-free operation at up to 10 Gbit/s as well as signal reshaping have been obtained with such devices. Besides the study of components, wavelength converters have been used in several demonstrators assessing their maturity and compatibility with photonic-switching applications.     

All-optical regeneration based on a nonlinear long period grating

We theoretically investigate a nonlinear all-optical switching scheme based on a long period grating written in a highly nonlinear chalcogenide fiber. We investigate the impact of two-photon absorption on the device and show that the influence of a modest amount of two photon absorption is actually beneficial to device performance as quantified by the power transfer function and improvement of the Q-factor of an incident signal.     

All-optical switching and routing based on an electromagnetically induced absorption grating

An electromagnetically induced absorption grating is formed in a three-level atomic vapor under the condition of electromagnetically induced transparency in which the strong coupling beam is replaced by a standing wave. The transmission and reflection behaviors of the weak probe beam are greatly modified at certain frequencies near the two-photon resonance. An all-optical two-port signal router-all-optical switch is demonstrated.     

All-optical switching of solitons in an active nonlinear directional coupler

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.     

All-optical switching of dark states in nonlinear coupled microring resonators

We propose and analyze an on-chip all-optical dynamic tuning scheme for coupled nonlinear resonators employing a single control beam injected in parallel with a signal beam. We show that the nonlinear Kerr response can be used to dynamically switch the spectral properties between a "dark state" and electromagnetically induced transparency configurations. Such a scheme can be realized in integrated optical applications for pulse trapping and delaying.     

A transmission line model for subwavelength metallic grating with single cut

A transmission line model for subwavelength metallic grating with single cut is presented. The model is based on analogy between the subwavelength metallic structure and the microwave transmission line theory. The analytical expression for the transmission is derived by the transfer matrix method. To confirm our model, the finite-difference time-domain (FDTD) method simulations are carried out. The influences of the position of the cuts on the higher modes of slit are presented. It is found that the transmission line model gives analytical prediction about the evolution of the transmission spectra.     

Plasmonic critical angle in optical transmission through subwavelength metallic gratings

We observe and theoretically analyze the plasmonic analog of the critical angle phenomenon in optical transmission through subwavelength gratings milled in an optically thick metal film. The total transmission from a denser medium to a less dense one vanishes while the total reflection holds very strong, providing the incidence angle increases past the plasmonic critical angle (PCA). The conditions and physical origins of the total internal reflection above the PCA are clarified.     

Nonreciprocal extraordinary optical transmission through subwavelength slits in metallic film

We demonstrate the phenomenon of nonreciprocal extraordinary optical transmission (NEOT) through metallic film with slits on the substrate of magneto-optical materials. Under uniformly magnetization, the system can show nonreciprocal transmission at near-IR frequency range. With a properly designed structure, the nonreciprocity can be as high as 57.6%. Numerical evidence shows that the nonreciprocal performance is sensitive to the incidence angle, as well as to the thickness of the substrate.     

基于多层膜结构的亚波长光栅研究

利用表面等离子体共振效应理论及金属-介质复合膜的特殊纳米光学效应对平面多层膜超分辨光刻技术进行了研究. 在曝光光源为365 nm的情况下,实现周期230 nm,线宽100 nm的超分辨光刻成像. 讨论了均匀金属-介质多层膜的结构参数选择,并通过数值仿真得到有效的光强度和对比度, 然后用等离子体纳米光刻进行试验验证,通过最优化选择,最终得到了亚波长结构多层膜的大区域范围超分辨成像.     

All-optical switching based on inverse Raman scattering in liquid-core optical fibers

We report on a new platform for all-optical switching based on inverse Raman scattering in liquids. Narrowband switching, which could be suitable for wavelength-division-multiplexed applications, is demonstrated using integrated liquid-core optical fiber infiltrated with both neat liquids (CCl(4) and CS(2)) as well as an organic chromophore (β-carotene) dissolved in CCl(4). Compared to standard glass optical fibers, these liquids have much larger Raman loss coefficients, which help reduce the pump power by at least an order of magnitude. Further improvements can be expected with the development of highly soluble organic compounds possessing large Raman cross sections.     

Optical bistability in nonlinear subwavelength metal hole array involving Kerr materials

We investigate an optical bistability phenomenon in a structure consisting of a silver film with a hole array filling with Kerr medium with single wavelength. We explore the mechanism of optical bistability in our structures and find that the excitation condition of surface plasmon at this moment is related with that at last moment. The contrast of optical bistability can reach to the maximum at the wavelength of the transmission peak. Our structure can realize the function of the beam splitter.