All-optical Circuits Research Articles

Proposed all-optical read-only memory element employing Si3N4 based optical microring resonator

All-optical processors and logic circuits are already doing wonders in the current research technologies. In connection to high-speed processors, this manuscript demonstrates a novel technique to implement an all-optical read-only memory element using an optical microring resonator. In the given article the authors have analysed the numerical modelling of Si3N4 based optical microring resonator (MRR). This silicon nitride-based MRR is modulated using an optical pumping signal which ultimately helps to achieve the optical switching through the constructed device using its nonlinear properties. The theoretical studies of the devices have been proved using simulation analysis. The obtained figures of merit like on-off ratio, extinction ratio, quality factor and finesse are very promising thus proves the practical feasibility of the proposed structure

Experimental verification of group non-membership in optical circuits

The class quantum Merlin–Arthur (QMA), as the quantum analog of nondeterministic polynomial time, contains the decision problems whose YES instance can be verified efficiently with a quantum computer. The problem of deciding the group non-membership (GNM) of a group element is conjectured to be a member of QMA. Previous works on the verification of GNM, which still lacks experimental demonstration, required a quantum circuit with O ( n 5 ) group oracle calls. Here, we provide an efficient way to verify GNM problems, in which each quantum circuit only contains O ( 1 ) group of oracle calls, and the number of qubits in each circuit is reduced by half. Based on this protocol, we then experimentally demonstrate the new verification process with a four-element group in an all-optical circuit. The new protocol is validated experimentally by observing a significant completeness-soundness gap between the probabilities of accepting elements in and outside the subgroup. This work efficiently simplifies the verification of GNM and is helpful in constructing more quantum protocols based on the near-term quantum devices.

A novel variable-length header extraction scheme based on ring laser for all-optical packet switching network

In this paper, a novel header extraction scheme based on a semiconductor ring laser is proposed and simulated for the proof of principle. This scheme is to be used in all-optical packet switching networks which can extract return-to-zero (RZ) modulation data packets with variable header/payload length and intensive spacing. Simulations and numerical analysis for a 3-byte header and 128-byte payload show that this structure can extract headers with more than a 20 dB contrast ratio. Additionally, the structure's simplicity and its small size makes it a proper candidate for integration with other all-optical circuits.

Ultra-compact Universal Linear-Optical Logic Gate Based on Single Rectangle Plasmonic Slot Nanoantenna

Optical logic gates are key elements in all-optical circuits and computing. However, the footprints of current optical logic gates are still on micrometer scale. There remains challenging for further miniaturization of the logic gates to nanometer scale. In this paper, a simple scheme for realizing ultra-compact universal linear-optical logic gates is proposed. All common logic gates (AND, OR, NOT, NAND, NOR, XOR, and XNOR) encoded via binary phase shift keying are achieved by using single rectangle plasmonic slot nanoantenna with a footprint of 200 nm by 50 nm, which considerably shrinks the dimensions of the device.

Tunable bandpass plasmonic filter based on graphene as the nonlinear Kerr material

In this paper, a band-pass plasmonic filter is introduced based on metal–insulator–metal waveguide coupled with two narrow slabs. Our reported plasmonic structure is investigated using the numerical solution of finite element method. The filter performance is analyzed for two cases of linear and nonlinear. The selected Kerr nonlinear material is a single graphene layer. The simulation results show that, we can tune the resonant wavelength by considering the Kerr effect of the graphene layer, performance and by adjusting the incident light signal without changing the physical characteristics of the structure. The simplicity of the structure and a compact size are the advantages of the proposed nonlinear plasmonic filter which make that suitable to design the integrated all-optical circuits.

Nonreciprocal Devices in Silicon Photonics

Nonreciprocal devices are crucial components for optical communications, nonlinear signal processing and all-optical circuits in silicon-compatible photonic platforms, but traditional techniques for achieving nonreciprocity and isolation have lacked CMOS compatibility. In recent work, we combined state-of-the-art fabrication and inverse design to demonstrate bias-free, low-loss nonreciprocal transmission in silicon integrated devices.

Numerical simulation of all-optical logic functions at micrometer scale by using plasmonic Metal-Insulator-Metal (MIM) waveguides

All-optical integrated circuits are quite useful in the regime of ultrafast computing to overcome the limitations of existing electronic components. In this work, we have modelled two different all-optical integrated circuits to validate the operations of OR, AND, NOR, XOR, XNOR logic gates and half-adder circuit. To cascade the integrated circuits, a plasmonic metal–insulator-metal (MIM) waveguide based Mach-Zehnder interferometer (MZI) has been used. The signal switching is attained by using MEH-PPV [poly(2-methoxy-5-(28-ethylhexyloxy)-PPV)] as nonlinear Kerr material in one linear arm of MZI. The relative linear permittivity, response time and RI of nonlinear Kerr material are 2.7225, 2.0 e−15 s, and 1.67, respectively. The switching of signal across the output ports of MZI depends on the principle of self-phase and cross-phase modulation, which depends on the power of input signals. Signal power of 0.326 W/µm and 0.828 W/µm is used for low and high intensity which corresponds to logic level ‘0′ and ‘1′, respectively. The projected integrated circuits are analyzed at the wavelength of 1550 nm with transverse magnetic (TM) polarization under the contour of perfect matched layer (PML) as boundary conditions. The results conclude that the extinction ratio (ER) of single MZI is gradually decreasing with respect to the increase in power difference. For proposed design of single MZI the attained value of ER is 24 dB at the power difference of 0.3 dB. The authentication of proposed integrated circuits is done by using finite difference time domain (FDTD) based method.

Coherent Interactions in One-Dimensional Topological Photonic Systems and Their Applications in All-Optical Logic Operation.

Topological photonics has become an active subfield of photonics analogous to the electronic counterpart, and the bulk-edge correspondence leads to robust topologically protected interfacial states. However, a single-topological interface mode with fixed energy cannot be easily manipulated, hindering its applications in optical devices. Here, we study coupled-waveguide arrays mapped to a one-dimensional Su-Schrieffer-Heeger system with two coupled topological interfaces. This configuration greatly increases device versatility and tunability while keeping the confinement of coupled-interface modes inherited from the topological properties nearly intact. Theoretically predicted oscillations between coupled interfaces is experimentally observed. The spatial and energetic isolation of the coupled interface states from the bulk modes is experimentally observed and theoretically confirmed by calculating the degree of localization of the eigenstates, which is found to be comparable to a single-interface state. Finally, a proof-of-principle, all-optical logic circuit is fabricated based on coupled interfaces, demonstrating its potential in assembling on-chip topological optical devices.

Polarization-selected nonlinearity transition in gold dolmens coupled to an epsilon-near-zero material

Abstract Nonlinear optical materials are cornerstones of modern optics including ultrafast lasers, optical computing, and harmonic generation. The nonlinear coefficients of optical materials suffer from limitations in strength and bandwidth. Also, the nonlinear performance is typically monotonous without polarization selectivity, and to date, no natural material has been found to possess nonlinear coefficients with positive or negative signs simultaneously at a specific wavelength, all of which impede practical applications in the specific scenario. Here, we realize broadband large optical nonlinearity accompanied with ultrafast dynamics in a coupled system composed of gold dolmens and an epsilon-near-zero material for dual orthogonal polarizations simultaneously. The system also shows the polarization-selected nonlinearity transition properties, where the sign of the optical nonlinear refractive indexes can be converted via polarization switching. This guarantees active transitions from self-focusing to self-defocusing by polarization rotation without tuning wavelength in practical utilizations. The measured nonlinear refractive index and susceptibility demonstrate more than three orders of magnitude enhancement over a 400-nm-bandwidth compared with the constituents, while maintaining the sub-1 ps time response. The realized enhanced, ultrafast response, and the polarization tunability ensure the designed system a promising platform for the development of integrated ultrafast laser sources, all-optical circuits and quantum chips.

Terahertz Spoof Surface Plasmonic Logic Gates.

SummaryLogic gates are important components in integrated photonic circuitry. Here, a series of logic gates to achieve fundamental logic operations based on linear interference in spoof surface plasmon polariton waveguides are demonstrated at terahertz frequencies. A metasurface-based plasmonic source is adopted to couple free-space terahertz radiation into surface waves, followed by a funnel-shaped metasurface to efficiently couple the surface waves to the waveguides built on a domino structure. A single Mach-Zehnder waveguide interferometer can work as logic gates for four logic functions: AND, NOT, OR, and XOR. By cascading two such interferometers, NAND and NOR operations can also be achieved. Experimental investigations are supported by numerical simulations, and good agreement is obtained. The logic gates have compact sizes and high intensity contrasts for the output “1” and “0” states. More complicated functions can be envisioned and will be of great value for future terahertz integrated computing.

Numerical analysis of tunable nonlinear plasmonic router based on nanoscale ring resonators

In the advanced plasmonics integrated circuits (PICs) there has been outstanding, continuing interest in developing routers to harness light-matter interactions in nanoscale dimensions with wanted optical properties. In this regard, herein, we introduce an all-optical router based on nanometer ring resonator which surface plasmon resonance (SPR) and nonlinear materials are used simultaneously to enhance high performance range. By changing the radius of the ring resonator and the intensity of the light we achieved control of the parameters and the routing. The results of routing and shifting the central frequency with light intensity and radius of the ring resonator are studied. The performance of the router indicates that a ring is required for each ports, which changes the control parameters to change its central frequency, as well as we can be said the use of switches and filters as other design features. These routers have advantages such as nano scale size, low light intensity, fast response time, integratable and etc., which are highly used in all-optical circuits, image processing and today's modern technology. In our simulation, we consider transmission or reflection of light in each ports based on the finite difference time domain (FDTD).

Optically Rewritable Memory in a Graphene–Ferroelectric-Photovoltaic Heterostructure

Achieving optical operation of logic elements, especially those that involve 2D layers, can open the long sought era of optical computing. However, the efficient optical modulation of the electronic properties of 2D materials including memory effect is currently missing. Here we report a fully optical control of the conductivity of a graphene with write/erase option yet under ultralow optical fluence. The competition between light-induced charge generation in ferroelectric-photovoltaic substrate with subsequent relaxation processes provides the selective photocarrier trapping control affecting the doping of 2D overlayer. These findings open the road to photonic control of 2D devices for all -optical modulators and a variety of all-optical logic circuits, memories and field-effect transistors.

Reversible and tunable photochemical switch based on plasmonic structure

For the first time, pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) is studied for realizing active plasmonic control, which is attracted considerable attention owing to its unique photophysical and photochemical properties. We have used this photoacid (HPTS) as an active surrounding medium that can be optically controlled and used for modulating plasmon resonances. In this paper, the fabrication of 2D-plasmonic grating coated by thin film of HPTS exposed to UV irradiation is reported. By switching the UV light on and off, the HPTS thin film maintains an excited-state proton transfer (ESPT) process followed by green fluorescence resulting in a plasmonic redshift caused by the variation of the refractive index. Furthermore, this photochemical active medium has also played another important role in plasmonic sensing, in which the emission-based response of HPTS thin film in 2D-plasmonic grating to water vapor upon photoexcitation is demonstrated, for both s and p polarizations. This tunable, flexible and reversible light-driven system will enhance the development of active plasmonic structures and will have a great influence on many fields such as, biochemical optical sensors and all-optical plasmonic circuits.

Logic Gates Based on Interaction of Counterpropagating Light in Microresonators

Optical logic has the potential to replace electronics with photonic circuits in applications for which optic-to-electronic conversion is impractical and for integrated all-optical circuits. Nonlinear optics in whispering gallery mode resonators provides low power, scalable methods to achieve optical logic. We demonstrate, for the first time, an all-optical, universal logic gate using counterpropagating light in which all signals have the same operating optical frequency. Such a device would make possible the routing of optical signals without the need for conversion into the electronic domain, thus reducing latency. The operating principle of the device is based on the Kerr interaction between counter-propagating beams in a whispering gallery mode resonator which induces a splitting between the resonance frequencies for the two propagating directions. Our gate uses a fused silica microrod resonator with a \textit{Q}-factor of $\SI{2e8}{}$. This method of optical logic gives a practical solution to the on-chip routing of light.

A novel proposal for an all-optical 2-bit adder/subtractor based on photonic crystal ring resonators

Optical addition and subtraction are very crucial functions required in all optical computations and processing. In this article we propose an all-optical circuit that can implement these functions simultaneously. The proposed device can be realized by combining optical XOR gates with a 2-bit full adder. Four nonlinear ring resonators are used to realize the proposed structure.

All-optical Half-Adder circuit with using spatial Optical solitons

All-optical Half-Adder circuit with using spatial Optical solitons

Chipscale plasmonic modulators and switches based on metal–insulator–metal waveguides with Ge2Sb2Te5

We introduce phase-change material Ge2Sb2Te5 (GST) into metal-insulator-metal (MIM) waveguide systems to realize chipscale plasmonic modulators and switches in the telecommunication band. Benefitting from the high contrast of optical properties between amorphous and crystalline GST, the three proposed structures can act as reconfigurable and non-volatile modulators and switches with excellent modulation depth 14 dB and fast response time in nanosecond, meanwhile possessing small footprints, simple frameworks and easy fabrication. This work provides new solutions to design active devices in MIM waveguide systems, and can find potential applications in more compact all-optical circuits for information processing and storage.

Design and analysis of a plasmonic demultiplexer based on band-stop filters using double-nanodisk-shaped resonators

In this paper, a two-channel plasmonic wavelength demultiplexer (PWDM) based on band-stop filters (BSF) using double-nanodisk-shaped resonators is proposed. The structure is numerically simulated using finite difference time domain method. First, a BSF is considered for modeling which supports three modes. Then, the effect of various structural parameters of the proposed PWDM is studied on the transmission properties in detail. The results show that the transmission properties of our PWDM are highly dependent on geometric parameters. The proposed structure provides a single-mode spectrum on each of the output ports with a maximum quality factor as high as 105 (FWHM = 7.7 nm). To this end, we illustrate that the concerning published research in this field, the significant privilege of our proposed PWDM structure is in terms of its good transmission efficiency, lowest FWHM and highest quality factor. Hence, such an arrangement is easy to fabricate and it has the potential for use in all-optical ultra-compact circuits and devices.

Electromagnetically induced transparency in an all-dielectric nano-metamaterial for slow light application.

Slow light technique has significant potential applications in many contemporary photonic device developments for integrated all-optical circuit, such as buffers, regenerators, switches and interferometers. In this paper, we present an efficient coupling mechanism of an electromagnetically induced transparency like (EIT-like) effect in an all-dielectric nano-metamaterial. This EIT-like effect is generated by destructive interference between a radiative Fabry-Perot (FP) mode and a dark waveguide (WG) mode, which is based on a combined structure of a dielectric grating and multilayer films. The dark WG mode is excited by guided mode of dielectric grating instead of radiative FP mode. In analogy to the molecular transition process, the FP mode, guided mode and WG mode are denoted by excited states of |1〉, |2〉 and |3〉. The two coupling pathways of the EIT-like effect in our metamaterial are |0〉 → |1〉 and |0〉 → |2〉 → |3〉 → |1〉, where |0〉 is the ground state. The simulated resonant wavelength of WG mode is consistent with theoretical result. We further confirm this EIT-like effect through a two-oscillator coupling analysis. We achieve a group refractive index of 913.6 by adjusting these two modes coupling of the EIT-like effect, which is useful for developing slow light device. This work provides a valuable solution to realize electromagnetically induced transparency in all-dielectric nanomaterial.

Evolution of Adder and Subtractor Circuit Using Si3N4 Microring Resonator

Abstract All-optical processor capable of processing optical bits has been a long-standing goal of photonics. In this paper, we report the results obtained by numerical simulations regarding the designing of an all-optical combinational circuit of an adder and subtractor circuits based on Si3N4 microring resonators. The designs of combinational circuit like adders and subtractor based on the use of all-optical basic logic gates are discussed while presenting the numerically simulated results. Extinction ratios of 5.2 dB, 3.5 dB and 2.7 dB are obtained for the half adder, full adder and half subtractor, respectively.