Photonic Label Research Articles

Droplet Lasers for Smart Photonic Labels.

Microscopic lasers represent a promising tool for the development of cutting-edge photonic devices thanks to their ability to enhance light–matter interaction at the microscale. In this work, we realize liquid microlasers with tunable emission by exploiting the self-formation of three-dimensional liquid droplets into a polymeric matrix driven by viscoelastic dewetting. We design a flexible device to be used as a smart photonic label which is detachable and reusable on various types of substrates such as paper or fabric. The innovative lasing emission mechanism proposed here is based on whispering gallery mode emission coupled to random lasing, the latter prompted by the inclusion of dielectric compounds into the active gain medium. The wide possibility of modulating the emission wavelength of the microlasers by acting on different parameters, such as the cavity size, type and volume fraction of the dielectrics, and gain medium, offers a multitude of spectroscopic encoding schemes for the realization of photonic barcodes and labels to be employed in anticounterfeiting applications and multiplexed bioassays.

Waveguide-type optical circuits for the recognition of optical 8PSK-coded labels

This paper discusses optical label recognition for photonic label routing. The label recognition is one of the key functions in photonic label routing related functions including optical label extraction, recognition of the label and label rewriting. In a previous study, we have proposed a basic waveguide-type circuit for the recognition of an optical label encoded in quadri-phase-shift-keying (QPSK) format, which consists of a 3-dB directional coupler, two Y-branches and an asymmetric X junction coupler. In order to increase the number of labels represented by the same symbol number, we propose 8PSK recognition circuits based on the QPSK recognition circuit. The input-output relation of the proposed circuits is theoretically discussed and the noise tolerance is also investigated. From the theoretical analysis, the proposed optical-waveguide circuits recognize the 8PSK labels by detecting the position of the output port having either the maximum or minimum intensity. The bit-error performance of the proposed circuits is clarified by computer simulation. It is found that the minimum-output detection scheme for a one-symbol 8PSK label is superior from the viewpoint of noise tolerance. The proposed method also addresses the scalability of two-symbol 8PSK coded labels. The maximum-output detection scheme demonstrates improved scalability performance.

Noise tolerance in optical waveguide circuits for recognition of optical 16 quadrature amplitude modulation codes

In photonic label routers, various optical signal processing functions are required; these include optical label extraction, recognition of the label, optical switching and buffering controlled by signals based on the label information and network routing tables, and label rewriting. Among these functions, we focus on photonic label recognition. We have proposed two kinds of optical waveguide circuits to recognize 16 quadrature amplitude modulation codes, i.e., recognition from the minimum output port and from the maximum output port. The recognition function was theoretically analyzed and numerically simulated by finite-difference beam-propagation method. We discuss noise tolerance in the circuit and show numerically simulated results to evaluate bit-error-rate (BER) characteristics against optical signal-to-noise ratio (OSNR). The OSNR required to obtain a BER less than 1.0×10−3 for the symbol rate of 2.5 GBaud was 14.5 and 27.0 dB for recognition from the minimum and maximum output, respectively.

Improvement of contrast ratio in quadriphase-shift-keying optical label recognition with passive optical waveguide circuit

In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed waveguide-type optical circuits for recognition of optical labels encoded in quadriphase-shift-keying (QPSK) form. A basic device for the circuits consists of a 3-dB directional coupler, two Y-branches, and an asymmetric X-junction coupler. We employed a scheme of complete interference of optical waves between each coded pulse and a reference pulse in our previously reported paper. The contrast ratio of the output at the destination output port to the outputs at the other ports was reported to decrease to 1.6, 1.28, and 1.13 for two-, three-, and four-stage circuits for recognition of 16, 64, and 256 QPSK labels, respectively. We find optimum circuits with improved contrast ratio of 1.8, 1.6, and 1.47 for 16, 64, and 256 labels, respectively. The recognition operation with the improved circuits is numerically confirmed using the beam propagation method. Noise tolerance of the proposed circuits is also clarified by numerical simulation. The improved circuits are optimum from the viewpoint of efficient use of optical power and noise tolerance.

Proposal of Optical Waveguide Circuits for Recognition of Optical QAM Codes

Optical processing of optical labels at high-bit rate is expected in broadband photonic label routers. So far, a variety of optical waveguide circuits and systems to recognize optical BPSK and QPSK coded labels have been studied. In this paper, we propose optical waveguide circuits to recognize optical 16QAM codes. The circuits consist of multi-stage connection of previously proposed circuit for QPSK code recognition. The recognition characteristics for 16QAM codes are theoretically analyzed. To confirm the recognition principle, FD-BPM simulation is performed with a two-dimensional model. Scaled circuits for recognition of 2-symbol 16QAM coded labels and 64QAM codes are also discussed.

Optical Label Routing Processing for BPSK Labels Using Complex-Valued Neural Network

Optical neural-network circuit to recognize BPSK labels for photonic label routing is proposed, whose neuron consists of optical amplitude amplifiers and phase shifters as weighting connections, a combiner and a nonlinear threshold device for an activation function. The parameters of these weighting connections are learned with back-propagation of teacher signals. The performance of the neural network circuits as recognition of two to four bit BPSK labels is clarified by computer simulation. For routing application, classification of routing labels into several groups corresponding to the output ports of the router is also discussed and is successfully simulated.

Passive Waveguide Device Consisting of Cascaded Asymmetric X-Junction Couplers for High-Contrast Recognition of Optical BPSK Labels

Fast all-optical processing is expected for packet routing in high-speed photonic networks. In photonic label networks, recognition of optical labels is one of the key functions. We propose a scalable passive waveguide device to recognize binary phase shift keying (BPSK) labels. The label recognition device consists of cascaded asymmetric X-junction couplers. The proposed basic device recognizes four labels consisting of parallel four pulses. Since an output is obtained at only one output port out of four ports with high contrast ratio, the device can be scaled up for labels of a larger number of bits. The devices for four, eight and sixteen labels are theoretically analyzed. To confirm the operation in the devices, the label recognition of four- and eight-bit labels is numerically simulated by finite-difference beam propagation method (FD-BPM). Expanded circuits based on the four-bit basic device to increase the number of recognizable labels are also presented.

Photochemically and Electrochemically Triggered Au Nanoparticles “Sponges”

Stimuli-triggered wettability of surfaces and controlled uptake and release of substrates by "smart" materials are essential for drug delivery and microfluidic control. A composite "sponge" consisting of bis-aniline-bridged Au nanoparticles (NPs), functionalized with photoisomerizable nitrospiropyran/nitromerocyanine that includes selective imprinted molecular recognition sites for N,N'-bis(3-sulfonatopropyl)-4,4'-bipyridinium (PVS) was electropolymerized on a Au electrode. The system is triggered by photonic and/or electrical signals to yield four different states exhibiting variable binding/release capacities for PVS and controlled wettability of the surface. The electrical/optical uptake and release of PVS to and from the Au NPs "sponge", respectively, is followed by CdSe/ZnS quantum dots, acting as an auxiliary photonic label.

Optimization of Two-Dimensional Filter in Time-to-Space Converted Correlator for Optical BPSK Label Recognition Using Genetic Algorithms

A two-dimensional filter for photonic label recognition system using time-to-space conversion and delay compensation was designed using Genetic-Algorithms (GA). For four-bit Binary Phase Shift Keying (BPSK) labels at 160Gbit/s, contrast ratio of the output for eight different labels was improved by optimization of two-dimentional filtering. The contrast ratio of auto-correlation to cross-correlation larger than 2.16 was obtained by computer simulation. This value is 22% larger than the value of 1.77 with the previously reported system using matched filters.

Wavelength Dependence of Optical Waveguide-Type Devices for Recognition of QPSK Routing Labels

In photonic label routing networks, recognition of optical labels is one of the key functions. We have proposed passive waveguide-type devices for recognition of optical labels coded in quadri-phase-shift-keying (QPSK) form. In this paper, we consider wavelength dependence of the devices. The basic module of the proposed device consists of a 3-dB directional coupler, two Y-junctions, and an asymmetric X-junction. The Y-junction and an asymmetric X-junction have basically no wavelength dependence. Although the 3-dB directional coupler has weak wavelength dependence, the device for two-symbol label recognition is found to work in wavelength 1.5-1.6 μm. The performance of the device is confirmed by simulation using beam propagation method (BPM).

Wavelength-Insensitive Integrated-Optic Circuit Consisting of Asymmetric X-Junction Couplers for Recognition of BPSK Labels

We have proposed a label recognition integrated-optic circuits for photonic label switching using self-routing of the label pulses. Binary phase shift keying (BPSK) format is considered as the label. An identifying bit is placed ahead of the address bits in the label. The label recognition system consists of a tree-structure connection of asymmetric X-junction couplers. The system uses self-routing propagation of the identification bit controlled by the address bits. Asymmetric X-junction couplers have a feature of small dependence on wavelength. However, the wavelength dependence of optical circuits consisting of multiple asymmetric X-junction couplers depends strongly on its architecture. In this paper, we propose a wavelength insensitive architecture of the recognition circuit. The wavelength independence in the improved circuit is confirmed using finite-difference beam propagation method (FD-BPM). We numerically demonstrate that our proposed system can recognize all the binary-code labels in wavelength range of 1500-1600 nm with crosstalk less than -25 dB and -15 dB for label length three and four, respectively.

Photonic Label Recognition by Time-Space Conversion and 2-D Spatial Filtering With Delay Compensation

An optical-label recognition system using time-to-space conversion, spatial Vander-Lugt 2-D correlation, and postprocessing with a slit and a delay compensator is proposed. The postprocessing, with the narrow slit and a prism for the time-delay compensation, makes it possible to distinguish the labels, consisting of a time series of optical pulses. For 4-b binary phase-shift-keying labels at 160 Gb/s, eight different labels are proved to be distinguished by the computer simulation. The contrast ratio of autocorrelation to cross-correlation is 1.61 and 2.5 without and with time gating, respectively.

Waveguide-Type Optical Circuit for Recognition of Optical QPSK Coded Labels in Photonic Router

In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a In photonic label routing networks, optical recognition of optical labels is one of the key functions. We propose a passive waveguide-type device for recognition of optical coded labels. We consider quadrature-phase-shift-keying (QPSK) coded labels. The basic module of the proposed device consists of a 3-dB directional coupler, two Y-junctions, and an asymmetric X-junction. By using interference between an optical pulse of each coded bit and a identifying bit pulse, the basic module distinguishes optical phase of the QPSK signal in a self-routing fashion of the identifying bit pulse. QPSK codes consisting of plural bits can also be recognized by connecting the basic module device in a tree structutre through a phase adjustment circuit. The performance of the proposed basic module is confirmed by simulation using beam propagation method (BPM).passive waveguide-type device for recognition of optical coded labels. We consider quadrature-phase-shift-keying (QPSK) coded labels. The basic module of the proposed device consists of a 3-dB directional coupler, two Y-junctions, and an asymmetric X-junction. By using interference between an optical pulse of each coded bit and a identifying bit pulse, the basic module distinguishes optical phase of the QPSK signal in a self-routing fashion of the identifying bit pulse. QPSK codes consisting of plural bits can also be recognized by connecting the basic module device in a tree structure through a phase adjustment circuit. The performance of the proposed basic module is confirmed by simulation using beam propagation method (BPM).

Recognition Characteristics of Layered Code for Optical Time-Series Wavelength-Division-Multiplexed Labels Using Collinear Acoustooptic Switch Arrays

Optical label processing is expected to be an important function in photonic label routing systems. Collinear acoustooptic (AO) devices have the potential to process wavelength-multiplexed optical signals. We discuss their application to label recognition systems using their feature of multiple-wavelength selectivity. We propose a system consisting of AO arrays, optical delay waveguides, and electrical multipliers for the recognition of optical codes encoded in wavelength and time domains. In particular, the scalability of the system for optical labels in a layered structure is described. An increase of the number of labels represented by optical codes and the application to layered routing control are expected.

Optical Label Recognition Using Tree-Structure Self-Routing Circuits Consisting of Asymmetric X-Junctions

We propose a new label recognition system for photonic label routing network. Binary-coded labels in binary phase-shift-keying format are considered. The system consists of an optical waveguide circuit with tree-structure passive asymmetric X-junctions and time gates. The system uses self-routing propagation of an identifying bit by performing interference with address bits. The identifying bit is placed in advance of the address bits in the label. The identifying bit pulse is routed to the destination output port corresponding to the code of the address. The operation principle is described. It is shown that all the binary number codes can be recognized with this system. We discuss the feasibility of the system by evaluating its crosstalk. To reduce the crosstalk, an improved scheme is also presented. The label recognition operation with the optical waveguide device is verified by numerical simulation using the finite-difference beam propagation method.

All-Optical Label Recognition Using Self-Routing Architecture of Mach-Zehnder Interferometer Optical Switches with Semiconductor Optical Amplifiers

We propose a new label recognition system for photonic label switching using self-routing of labels. Binary-coded labels in on-off keying format are considered. The system consists of an all-optical demultiplexer (DeMUX) and an address recognition unit (ARU) consisting of tree-structured switches. The system uses self-routing propagation of an indication bit controlled with address bits. The indication bit is placed in advance of the address bits in the label. In DeMUX, all-optical switches in a configuration of Mach-Zehnder interferometer with semiconductor optical amplifiers (SOA-MZI) are controlled by the indication bit pulse to separate each of the label bits. The indication bit pulse is routed to the destination output port corresponding to the code of the address in ARU. It is shown that all the binary number codes can be recognized with this system. The operation principle is verified by numerical simulation using coupled-mode theory and a rate equation. Moreover, the switching crosstalk is also evaluated.

Analysis of Optical Processing for Recognition of BPSK Optical Codes Using Collinear Acoustooptic Switches for Photonic Routing Network

Optical processing with efficient coding is expected in photonic label routing network. We consider optical codes encoded in the time and spectral domains. Wavelength-selective devices are useful for effective processing of such optical codes. In this study, collinear acoustooptic (AO) switches are investigated as a constituent elements of a wavelength selective correlator for optical BPSK codes. It is theoretically shown that the number of optical codes that can be distinguished is 2 Nt-1 , where N t is the bit number of optical pulses. The device can also be used for recognition of codes encoded in time and spectral domains. Crosstalk in code recognition is discussed with numerical analysis considering AO filtering characteristics for optical processing with collinear AO devices.

A Packet-Based Photonic Label Switching Router for a Multirate All-Optical CDMA-Based GMPLS Switch

A novel packet-based photonic label switching router for a multirate all-optical switch using generalized multiprotocol label switching is proposed. The idea is based on using optical code-division multiple access (OCDMA) as multiplexing technique and treating OCDMA codes as labels. The system can coexist with current wavelength division multiplexing systems on the same infrastructure. The concept of switch fabric is introduced. Label processing and label swapping functionalities of the switch are discussed. In-depth analyses are made for spectrally phase-encoded OCDMA (SPE-OCDMA) due to its capabilities of supporting high data rates, large code cardinality, and its secure transmission. Packet loss rate for a multirate SPE-OCDMA system is derived. Some performance metrics are derived for a typical network via simulation, and the results are discussed.

Configurational design of a pair-controlled photonic switch fabric for both-way communications

Generally pair control architecture is adopted in telecommunication systems to save software processing time to setup both-way paths between a sender and a receiver. We have introduced this into a photonic switch fabric (PSF), which is a key instrument of a developed photonic label switch router (PLSR). The PLSR is to be operated as a photonic router in an optical Internet system to guarantee QoS (quality of service) and the transmission bandwidth by providing end-to-end wavelength LSPs (label switched paths). In contrast to conventional PSFs for both-way communications that do not have the capability to save switching elements and its control circuits, the proposed architecture enables us to save them drastically. General configuration of an N×N PSF is described in addition to the developed 3×3 PSF.

Network design and cost optimization for label switched multilayer photonic IP networks

Dealing with the explosive increase in the amount of Internet traffic requires high-speed and huge capacity Internet protocol (IP) backbone networks. Existing IP backbone networks are constructed using point-to-point wavelength-division-multiplexing (WDM) transmission systems, where all the wavelengths are terminated link-by-link, so that rather expensive optical/electrical conversions are necessary at every node. In these systems, since every IP packet is routed at each intermediate node based on the header information, a header processing bottleneck will occur when the node input traffic exceeds several hundreds of gigabits per second. In order to mitigate these problems, an optical cross-connect (OXC) function that employs wavelength routing of the optical paths (OPs) will provide an effective solution. This paper proposes a network design method where electrical and photonic multiprotocol label switching (MPLS) technologies are used; the network is referred to as a photonic IP network. We first propose new algorithms that minimize the network cost in a multilayered network comprising electrical label switched paths (LSPs) and optical LSPs (optical paths that are controlled using the MPLS mechanism). The particular point of the proposed algorithms is that they include different cost minimization scenarios appropriate for the different OLSP provisioning conditions that are chosen as the first step in the design stage. The effectiveness of the proposed algorithms and the benefits of the OLSPs are quantitatively evaluated through various simulations.