Multichannel Optical Switch Research Articles

Controlled multiple spectral hole burning via a tripod-type atomic medium

In limit of saturation spectroscopy, we theoretically study the spectral hole burning (SHB) in the absorption spectrum of a probe field through a tripod atomic system. The response function for the probe field is calculated in a Doppler-broadened medium. Burning of spectral holes is observed only for the counter propagation of either one or both the coupling fields in the medium. The SHB is not observed below some critical temperature which is a condition for the electromagnetically induced transparency (EIT) in the medium. The most interesting and significant feature is that the Doppler broadening acts as a decoherence effect in case of EIT, however, the Doppler broadening acts inversely in case of SHB and consequently the burning effect enhances. The SHB is further enhanced and controlled by classes of the average velocity of atoms. The classes of high average atomic velocity in the medium increase the number of spectral hole burns (HBs). The widths of HBs can be controlled by the intensity of the driving fields. A single HB can be switched to multiple HBs in a well-controlled manner using different classes of high average atomic velocity. The various switchable holes can be burned in a desired position of the absorption spectrum which in turn simultaneously slow down multiple probe fields. The phenomenon of SHB may be useful in the construction of multichannel optical switching and storage devices.

Multi-channel optical switching based on scanning mirror instrumentation

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Graphene Nanoribbon Gap Waveguides for Dispersionless and Low-Loss Propagation with Deep-Subwavelength Confinement.

Surface plasmon polaritons (SPPs) have been attracting considerable attention owing to their unique capabilities of manipulating light. However, the intractable dispersion and high loss are two major obstacles for attaining high-performance plasmonic devices. Here, a graphene nanoribbon gap waveguide (GNRGW) is proposed for guiding dispersionless gap SPPs (GSPPs) with deep-subwavelength confinement and low loss. An analytical model is developed to analyze the GSPPs, in which a reflection phase shift is employed to successfully deal with the influence caused by the boundaries of the graphene nanoribbon (GNR). It is demonstrated that a pulse with a 4 μm bandwidth and a 10 nm mode width can propagate in the linear passive system without waveform distortion, which is very robust against the shape change of the GNR. The decrease in the pulse amplitude is only 10% for a propagation distance of 1 μm. Furthermore, an array consisting of several GNRGWs is employed as a multichannel optical switch. When the separation is larger than 40 nm, each channel can be controlled independently by tuning the chemical potential of the corresponding GNR. The proposed GNRGW may raise great interest in studying dispersionless and low-loss nanophotonic devices, with potential applications in the distortionless transmission of nanoscale signals, electro-optic nanocircuits, and high-density on-chip communications.

Triple plasmon-induced transparency and outstanding slow-light in quasi-continuous monolayer graphene structure

We propose a simple quasi-continuous monolayer graphene structure and achieve a dynamically tunable triple plasmon-induced transparency (PIT) effect in the proposed structure. Additional analyses indicate that the proposed structure contains a self-constructed bright-dark-dark mode system. A uniform theoretical model is introduced to investigate the spectral response characteristics and slow light-effects in the proposed system, and the theoretical and the simulated results exhibit high consistency. In addition, the influences of the Fermi level and the carrier mobility of graphene on transmission spectra are discussed. It is found that each PIT window exhibits an independent dynamical adjustability owing to the quasi-continuity of the proposed structure. Finally, the slow-light effects are investigated based on the calculation of the group refractive index and phase shift. It is found that the structure displays excellent slow-light effects near the PIT windows with high-group indices, and the maximum group index of each PIT window exceeds 1000 when the carrier mobility of graphene increases to 3.5 m2 V−1 s−1. The proposed structure has potential to be used in multichannel filters, optical switches, modulators, and slow light devices. Additionally, the established theoretical model lays a theoretical basis for research on multimode coupling effects.

Self-Configuring and Reconfigurable Silicon Photonic Signal Processor

Photonic signal processing is essential in the optical communication and optical computing. Numerous photonic signal processors have been proposed, but most of them exhibit limited reconfigurability and automaticity. A feature of fully automatic implementation and intelligent response is highly desirable for the multipurpose photonic signal processors. Here, we report and experimentally demonstrate a fully self-learning and reconfigurable photonic signal processor based on an optical neural network chip. The proposed photonic signal processor is capable of performing various functions including multichannel optical switching, optical multiple-input-multiple-output descrambler and tunable optical filter. All the functions are achieved by complete self-learning. Our demonstration suggests great potential for chip-scale fully programmable optical signal processing with artificial intelligence.

Transmission investigation of one-dimensional Fibonacci-based quasi-periodic photonic crystals including nanocomposite material and plasma

In this communication, the transmittance characteristics of one dimensional quasi-periodic photonic crystals (PCs) is investigated. The proposed structure consists basically of plasma and nanocomposite layers arranged in accordance to the Fibonacci sequence. The effect of volume density of the plasma and the volume fraction of the nanocomposite material on the properties of the photonic band gaps are studied in detail. The effect of layers thicknesses and the sequence number are also taken into account. We believe that such structures can be potentially beneficial in many novel future applications such as multichannel and pass band filters and optical switches. Additionally, such PCs can be used to design tunable optical devises through controlling the plasma and nanoparticle densities.

Tunable Triple-Band Plasmonically Induced Transparency Effects Based on Double π-Shaped Metamaterial Resonators

Tunable triple-peaks with the transmission intensity of more than 90% plasmonically induced transparency metamaterial resonator based on nested double π-shaped metallic structure is proposed at the terahertz frequency region, which is consisted of three sets of gold nanorods with different sizes placed on a dielectric substrate of SiO2. The coupling effect of localized electric field between different parts of the proposed structure can be used to explain the physical mechanism of three transparent windows. The finite-difference time-domain (FDTD) is used to study the spectral properties of the proposed structure, and the influence of the size of the nanorods and the relative distance between them on the spectral characteristics are also discussed. It can be seen that some obvious shift phenomena occur in the spectra with the change of these nanorods. These results indicate that the proposed structure opens up new avenues in many related applications, especially for multi-channel filters, optical switches, and sensors.

Coupling effects in single-mode and multimode resonator-coupled system.

We have proposed a simple metal-dielectric-metal (MDM) waveguide system side-coupled with single-mode and multimode resonators. This proposed structure can achieve a typical dual plasmon-induced transparency (PIT) effect in the transmission spectra. The two PIT peaks exhibit opposite evolution tendencies with the increase in the depth of stubs. A multimode-coupled mode theory (M-CMT), confirmed by simulated results, is originally introduced to investigate the coupling effects of the proposed structure. Compared to the previous reported multichannel filters, the proposed structure includes obvious advantages, such as structural simplicity and ease of fabrication. In addition, the sensing characteristics of the proposed structure based on PIT effects are discussed numerically. The results demonstrate that the proposed structure is suitable for applications in multichannel filters, optical switches, and sensors.

Transmittance properties of a quasi-periodic one-dimensional photonic crystals that incorporate nanocomposite material

In this paper, we investigate theoretically the transmission properties of one-dimensional quasi-periodic photonic crystals that containing nanocomposite material in the IR wavelength regions. Our structure is particularly designed using the Fibonacci role. Here, the nanocomposite material is composed of nanoparticles of Ag that are randomly immersed in a host dielectric material of SiO2. Numerical results are mainly investigated based on the well-known characteristic matrix method. The numerical results show the appearance of many photonic bandgaps due to the multiple periodicities of our structure. Furthermore, the effects of the parameters of the nanocomposite such as the volume fraction, the refractive index of the dielectric material and the size of the nanoparticles have distinct effects on the transmittance characteristics of our structure. Wherefore, the proposed structure could be considered the cornerstone for many applications such as multichannel filters and optical switches.

Multiple plasmon-induced transparency effects in a multimode-cavity-coupled metal–dielectric–metal waveguide

We numerically and theoretically investigate multiple plasmon-induced transparency (PIT) effects in a multimode-cavity-coupled metal–dielectric–metal (MDM) waveguide system. The introduced multimode coupled-radiating oscillator theory (MC-ROT) gives a clear understanding of multiple PIT effects in the proposed system. Two and three PIT peaks appear in the transmission spectra corresponding to the symmetrical and asymmetrical structures, respectively. Evolution of the PIT peaks can be effectively tuned by adjusting the geometric dimensions and asymmetry of the structure. The ultra-compact plasmonic waveguide structure may have important applications for multichannel filters, optical switches, and other devices in integrated optical circuits.

Super-Strong Photonic Localizations in Symmetric Defect Waveguide-Ring Networks

Super-strong photonic localizations that occur in symmetric defect waveguide-ring networks (SDWRNs) are presented in this study. It is found that the intensity of maximal photonic localization can increase as an exponential function with the number of rings and as a power function with the breaking degree of a defect in SDWRNs. Compared with previous reported results, SDWRNs can generate stronger photonic localizations and possess simpler structures. The fitting formulas of the intensity have been obtained. Moreover, the intensity, site number, and site positions for the maximal photonic localization can be adjusted by changing structural parameters in SDWRNs. The study may provide attractive applications as multichannel high efficiency energy storages, narrow-bandwidth filters, optical switches, and other correlative optical devices.

Tunable optical filters and multichannel switches based on MIM plasmonic nanodisk resonators inset a silver bar

A tunable band-stop filter and an unusual multichannel optical switch based on metal-insulator-metal (MIM) plasmonic nanodisk resonators with an inset silver bar are proposed and investigated numerically by using the finite-difference time-domain (FDTD) method. Simulation results reveal that the transmission spectrum of the filter can be tuned and modified efficiently not only by varying the width and length of the silver bar but also by rotating the silver bar. The refractive index of the dielectric surrounding the silver bar is changed for realizing the tunability of a broad stopband. Rotating the silver bar makes the surface plasmon polaritons (SPPs) pass different outputs of the multichannel optical switch. In all calculations, the outer size of the nanodisk is unchanged. The proposed structures will undoubtedly be useful for optical filtering and switching in ultra-compact plasmonic devices.

Dense Multi-Channel Optical Waveguide Switch Based on Micro Ring Resonators

This study proposes a dense multichannel optical waveguide switch based on micro ring resonators (MRRs). The proposed design is achieved by cascading five MRRs of the same structure and the phase difference between two bus waveguides that are evanescently coupled to every two MRRs is purposely set at either 0 or π in order to minutely adjusting the positions of the corresponding resonant wavelengths of the MRRs. Our proposed structure is capable of controlling ON/OFF signals associated with four optical channels. Our study finds that the resonant channel spacing is less than twice the full-width-at-half-maximum of an individual optical signal. Furthermore, among 16 different combinations of output spectra obtained, the ON/OFF signal contrast of each optical channel could reach up to -29.68 dB.

Electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system

The electro-optical channel drop switching in a photonic crystal waveguide-cavity side-coupling system is reported. The line waveguide is formed by removing a single row of dielectric cylinders. The twin optical microcavities side coupled between linear waveguides is studied by solving Maxwell's equations. We determine the general characteristics of the coupling element required to achieve channel drop tunneling. By modulating the conductance of the twin microcavities, the electrical tunability of the resonant modes is observed in the transmission spectrum. The spectral characteristics suggest a potential application for this switching device as an efficient multichannel optical switch in the photonic integrated circuits.

Tunable multiple all-optical switch based on multi-nanoresonator-coupled waveguide systems containing Kerr material

By using a 2-D finite difference time domain and transfer matrix method, we have theoretically and numerically analyzed the optical transmission characteristics of optical waveguide coupling to ring cavity array. The simulation results reveal that the dual-ring cavity waveguide configuration with Kerr nonlinear material can act as a double channel all-optical switch. The contrast ratio of the two switch channels is 16.6dB and 10.37dB, respectively. We also designed a bidirectional all-optical switch based on two parallel waveguides coupled to ring cavity structure. In addition, multi-channel optical switches are achieved by increasing the number of cavity. The designed all optical switching models will be helpful to dynamic control of light in photonic circuits.

Free-Space Optoelectronic Switching Cores With MPLS for SANs Over WDM Ring Networks

With increasing demands on storage devices in the modern communication environment, the storage area network (SAN) has evolved to provide a direct connection allowing these storage devices to be accessed efficiently. To optimize the performance of a SAN, a three-stage hybrid electronic/optical switching node architecture based on the concept of a MPLS label switching mechanism, aimed at serving as a multi-protocol label switching (MPLS) ingress label edge router (LER) for a SAN-enabled application, has been designed. New shutter-based free-space multi-channel optical switching cores are employed as the core switch fabric to solve the packet contention and switching path conflict problems. The system-level node architecture design constraints are evaluated through self-similar traffic sourced from real gigabit Ethernet network traces and storage systems. The extension performance of a SAN over a proposed WDM ring network, aimed at serving as an MPLS-enabled transport network, is also presented and demonstrated.

Tunable bi-functional photonic device based on one-dimensional photonic crystal infiltrated with a bistable liquid-crystal layer

We investigated the optical properties of a one-dimensional photonic crystal infiltrated with a bistable chiral tilted homeotropic nematic liquid crystal as the central defect layer. By modulating the nematic director orientation with applied voltage, the electrical tunability of the defect modes was observed in the transmission spectrum. The composite not only is a general tunable device but also involves the green concept in that it can operate in two stable states at 0 V. Under the parallel-polarizer scheme, the spectral characteristics suggest a potential application for this device as an energy-efficient multichannel optical switch.

Optoelectronic switches based on diffusive conduction

We study the process of diffusive conduction that we use in our optoelectronic switches to achieve rapid optical switching (on a picosecond time scale). We present the characteristic Green’s function of the diffusive conduction derived for arbitrary initial conditions. We also report the series solutions of the diffusive conduction obtained for different boundary conditions (V=0 and ∇V=0 along the device contact lines) in different device geometries (rectangular and circular mesas). Using these analytical results, we investigate the effect of boundary conditions on the switching operation and the steady state behavior in optical links. We demonstrate the feasibility of using such diffusive conductive optoelectronic switches to establish optical links in return-to-zero and non-return-to-zero coding schemes. For multichannel optical switching, we discuss possible use of a single optoelectronic switch to accommodate multiple channels at once, with >100 optical channels (with a 2000mm−2 channel density and <10% cross-talk), predicted on a 300×300μm2 mesa with a device switching bandwidth of >50GHz, leading to a 5Tb∕s aggregate transmission in principle. This approach of using multiple parallel channels on a single switch is completely opposite to the traditional idea of arraying many switches. This proposed scheme eliminates the need for on-chip switch integration and the need for the alignment of the optical channels to the integrated individual switches.

Piezoelectric actuated multiple channels optical switch

In this article, a novel multi-channel optical switch that is composed of a Y-shaped micromirror with two symmetrically reflective surfaces, a fixed pivot for mounting the micromirror, and a piezoelectric actuator to actuate the micromirror, is proposed. Working principle of this novel device is that the switching displacement of the reflective beam of light can be linearly controlled by the displacement of the piezoelectric actuator. Accordingly, the 1×N switching task can be easily achieved. To realize the proposed concept, UV-LIGA technique was implemented to fabricate the components. Multiple-switching concept was demonstrated through experiments. Efficiency of the proposed optical switch was investigated by computer simulations. Optical efficiency of the proposed device can be optimized if its dimensions are adequately designed.

High Speed Multi-channel MEMS Optical Switch

High Speed Multi-channel MEMS Optical Switch