Optical Label Research Articles

Flexible Optical Code Label Generation and Processing Using LiNbO<formula formulatype="inline"><tex Notation="TeX">$_{3}$</tex> </formula> Modulators and Variable Bandwidth Spectrum Shaper

We proposed and demonstrated flexible optical code label generation and processing using LiNbO <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$_{3}$</tex> </formula> (LN) modulators and a variable-bandwidth spectrum shaper. First we used a transversal filter (TVF) as a decoder and performed a simulation of optical encoding and decoding to confirm basic code characteristics by taking into consideration the characteristics of O/E conversion and threshold processing. The experiments were performed using with 4 chip, 10 Gchip/s BPSK codes to verify the simulation results. We found that these codes had sufficient threshold margins for code discrimination in the simulation, and this result was in good agreement with experimental results. Then, to handle variable BPSK codes, we used LN modulators as an encoder and a TVF as a decoder. To handle more variable BPSK codes, we proposed and experimentally demonstrated optical code generation and processing using LN modulators and a variable-bandwidth spectrum shaper (VBS). This method is capable of flexible optical encoding and decoding and high-precision control in the spectral domain. We confirmed correct discrimination between matched and unmatched coded by threshold processing in a simulation and experiment using 8 chip, 20 Gchip/s codes. Finally, by encoding pulses in the Non-Return-to-Zero (NRZ) format, we increased the number of discriminable coded with 8 chip, 40 Gchip/s NRZ BPSK codes.

FPGA-Based Label Processor for Low Latency and Large Port Count Optical Packet Switches

We present a field-programmable gate array (FPGA)-based label processor for in-band optical labels with a processing time independent of the number of label bits. This allows for implementing an optical packet switching architecture that scales to a large port count without compromising the latency. As a proof of concept, we have employed an FPGA board with 100 MHz clock to validate the operation of the label processor in a 160 Gb/s optical packet switching system. Experimental results show successful three label bits processing and 160 Gb/s packets switching with 1 dB power penalty and 470 ns of latency. Projections on the label processor performance by using more powerful FPGAs indicate that 60 label bits ( optical addresses) can be processed within 31 ns.

Virtual Optical Buffers: A Novel Interpretation of OCDMA in Packet Switch Networks

Among all proposed structures for optical networks, the optical packet switching (OPS) scheme, due to its practical implementation of IPs in an optical configuration and the consequent advantages, is a prizeworthy candidate for being employed in metropolitan area network and local area network communication levels. One of the few problems frequently met using the OPS structure in the fiber-optics realm is the lack of optical buffers, thus deteriorating the system's flexibility and quality of service. For example, optical label switching networks that have been developed recently based on the generalized multiprotocol label switching protocol, profoundly suffer from this setback which is considered as a great hurdle in their evolution. In this paper, we first introduce the input and output buffer switching models while deducing their blocking probability formulations. Then, by utilizing codes in the OPS structure, we closely examine the potential of code and/or wavelength switching in packet switching networks and also determine their blocking probability. Due to close similarities between different scenarios, we present the prospect of virtual optical buffers using codes, which have close performance to input and output buffers in sight of block probability. The most significant distinction in using virtual buffers is the fact that due to their substantial nature, they happen to exhibit some error probability. However, on account of the advantageous features of codes, the simulated and formulated error probability for both coherent and noncoherent optical code division multiple access (OCDMA), such as Spectrally phase encoded OCDMA and optical orthogonal codes, using virtual buffers, tends to be negligible. Two main code and wavelength switching schemes are also brought to attention in this work, the intelligent and random methods. These scenarios demonstrate an even greater behavioral performance to that of the mere code switching scenario, leading into a more reliable adaptation of virtual buffers. In addition, simulations results happen to provide clear verifications to our analytical approach.

Optical RF Tone In-Band Labeling for Large-Scale and Low-Latency Optical Packet Switches

We propose an RF tone in-band labeling technique that is able to support large-scale and low-latency optical packet switch. This approach is based on N in-band wavelengths, each carrying M radio frequency (RF) tones. The wavelengths and the tones have a binary value, and are able to encode 2N×M possible routing address. We develop an optical label processor for the RF tone in-band optical label based on parallel and asynchronous processing. It allows the optical packet switch with an exponential increase of number of ports at the expense of limited increase in the latency and the complexity. By using RF tone in-band labeling technique, we demonstrate error free (bit error rate <; 10-9) optical packet switching operation for both 160 Gb/s packets and 40 Gb/s packets. We further investigate the scalability, the latency and the optical power fluctuation tolerance of the proposed RF tone in-band labeling technique. We show that 30 label bits are able to be delivered using single in-band wavelength, and the label processor introduces an extra latency of less than 7 ns.

Nonlinear Optical Signal Processing in Optical Packet Switching Systems

This paper discusses nonlinear optical signal processing employed in optical packet switching systems. Nonlinear optical signal processing provides optical label (header) recognition, optical switching, wavelength conversion, and time buffering with typically higher capacity, lower latency, and lower power consumption than electronic counterparts. In order to provide diverse signal processing functions, large-scale integration of nonlinear optical signal processing devices is essential. We discuss possible future directions in optical packet switching involving nonlinear optical signal processing of optical packets with advanced data and label modulation formats.

A novel orthogonal modulation format of D8PSK/ASK with differential bi-phase encoding and its application in a label switching optical network

The principle of a novel orthogonal modulation format of differential 8-level phase-shift keying amplitude-shift keying (D8PSK/ASK) with differential bi-phase encoding (DBC) is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results are compared with other current schemes, and the effects of transmission range, modulation extinction ratio (ER) and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate (BER) are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.

In Vivo pH Imaging with 99mTc-pHLIP

A novel molecular imaging agent has been developed recently, which stains tissues of low extracellular pH [pH (low) insertion peptide, pHLIP(®)]. A pH-dependent process of peptide folding and insertion into cell membranes has been found in vitro. Targeting of acidic solid tumours has been demonstrated in vivo using fluorescence and PET labels. Here, we present proof of feasibility studies of pHLIP with a single-photon emission computed tomography (SPECT) label, (99m)Tc-AH114567, with focus on preclinical efficacy and imageability. Lewis lung carcinoma, lymph node carcinoma of the prostate and prostate adenocarcinoma tumour xenografts were grown in mice and characterised by the angiogenesis marker (99m)Tc-NC100692 and by extracellular pH measurements with (31)P-MRS of 3-aminopropyl phosphonate. Biodistribution was assessed and CT/SPECT imaging performed. Oral administration of bicarbonate served as control. Tc-AH114567 can be obtained via a robust synthesis with good radiolabelling profile and improved formulation. The tracer retains the pH-dependent ability to insert into membranes and to target tumours with similar pharmacokinetics and efficacy that had been demonstrated earlier for pHLIP with optical or (64)Cu PET labels. Despite the inherent challenges of SPECT compared to optical and PET imaging, e.g., in terms of lower sensitivity, (99m)Tc-AH114567 shows adequate image quality and contrast. The main development need for transitioning SPECT labelled pHLIP into the clinic is more rapid background signal reduction, which will be the focus of a subsequent optimisation study.

Photomodulation of Fluorescent Upconverting Nanoparticle Markers in Live Organisms by Using Molecular Switches

Although fluorescence microscopy continues to be the method of choice by biomedical researchers to reconstruct images of cells and tissues containing optical labels, [1] there still exist many limitations. The diffraction of light imposes the major drawback and reduces the spatial resolution achievable by conventional microscopes, which cannot distinguish between molecular or nanoscale probes residing in close proximity to each other. This limitation can be overcome by multiphoton approaches and the help of molecular switches that, by undergoing reversible photoreactions between two isomers with different absorption properties, can

Novel optical packet switching scheme using OFDM label with one core router and two edge routers

In this paper, we propose and experimentally demonstrate a novel optical packet switching scheme with one core router and two edge routers, in which an orthogonal frequency division multiplexing (OFDM) signal is generated as a label. In this experiment there are two transmission spans, each span consists of 50-km SMF-28 and an erbium-doped optical fiber amplifier (EDFA) without dispersion management. A 10Gb/s on-off keying (OOK) optical payload and a 2.5Gb/s OFDM optical label are generated, encapsulated, and transmitted in the first span. And then old label is replaced by new label, the generated new optical packet after transmission over the second span is detached and detected. The transmission performance of the optical label and payload is experimentally investigated at the ingress router, core router and egress router.

Proses Pengiriman Paket IP Menggunakan All Optical Label Swapping (AOLS)

Transmission IP packet into WDM network will experience of encapsulation process at Data Link Layer with adding overhead to packet. IP packet through Gigabit Ethernet have more less overhead than ATM. The usage of All Optical Label Swapping (AOLS) technology for transmitting IP packet into WDM network with using label swapping will add optical label to packet. At AOLS, process routing decision is to be done with only processing the optic label. During that process data payload constantly within optic domain. Key word : ATM, Gigabit Ethernet, AOLS, optic label.

A Novel Scheme of Generating Optical Packets in OLS System

The generation, extraction, identification and regeneration of optical label is one of the key problems in optical label switching technology. This paper proposes an optical labeling technique based on the use of CSRZ-DPSK modulation for the high-rate payload data and Manchester-SCM for the label information, and then analyzes its performance. Simulation results show that the optimal SC frequency is equal to payload rate or its half and label rate will affect the receiving of payload signal.

Calf thymus DNA-stabilized polythiophene fluorescence probe for label-free detection of spermine

It is a challenge to detect molecules lacking a chromophore, such as polyamines, by optical methods since they are insensitive to light. In order to detect the optical signals, it is compulsory to derive these molecules with optical labels, which, however, is complicated, time-consuming and may be expensive. In this work, a highly specific strategy for spermine detection is developed on the basis of the iodide-induced conformational change of polythiophene. By using the triplex complex of negatively charged double-stranded calf thymus DNA (ctDNA)-stabilized cationic polythiophene as a fluorescent probe, the highly specific detection of spermine could be realized since polythiophene, which will be released from the triplex complex owing to the condensation and aggregation of ctDNA with spermine, undergoes a conformational change from the random-coiled non-planar state to the highly conjugated planar form in the presence of iodide, resulting in a yellow-to-red color conversion and fluorescence quenching. The quenched fluorescence was found to be proportional to the spermine concentrations in the range of 1.2-50 μM with the limit of detection (LOD) being 0.5 μM (3σ/k).

Semiconductor Quantum Dots for Biomedicial Applications

Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can be used as labels for the electrochemical detection of DNA or proteins. This article reviews the synthesis and toxicity of QDs and their optical and electrochemical bioanalytical applications. Especially the application of QDs in biomedicine such as delivering, cell targeting and imaging for cancer research, and in vivo photodynamic therapy (PDT) of cancer are briefly discussed.

Cost Analysis in Optical Burst Switching Networks with Optical Label Processing

The aim of this work is the analysis of optical burst switching (OBS) networks with optical label processing based on optical code division multiplexing (OCDM) technology. An architecture of resource reservation based on just-in-time (JIT) was proposed and the blocking probability of burst loss considering the number of wavelength and traffic characteristics. Also, a cost model to compare the traditional electronic processing and optical processing was developed. The main results have showed the decrease of burst loss and economy of network resources when optical processing is utilized.

A novel architecture of optical code label processing in parallel designed for all optical routing system

A novel architecture of optical code label routing is designed based on optical code division multiplexing techniques, which performs the data packet forwarding and processing in parallel with a way of making the label and payload encoded and decoded separately. It uses optical polarity characteristics to realize the separation of the label and payload, employs fiber Bragg grating to encode/decode the label and payload so as to process them in parallel, and makes the forwarding and routing process realized in the optical domain. In the core router, the separation of the label and payload guarantees that the switch processing only includes the short label code recognition, without processing the payload. The payload recognition is carried out in the edge router. Thus, the router can simplify the processing of encoding and decoding in the core router, accelerating the switching, and increase the throughput greatly. Moreover, the novel routing scheme not only supports the varying of data packets, transparent transmission, fine granularity switching, and so on, but also is suitable for the aggregation of data service. It is attractive for the future development of all optical routing.

Gold nanoparticle probes: Design and in vitro applications in cancer cell culture

A new architecture has been designed by the conjugation of [ 18F]2-fluoro-2-deoxy- d-glucose ( 18F-FDG), gold nanoparticles (AuNPs), and anti-metadherin (Anti-MTDH) antibody which is specific to the metadherin (MTDH) over-expressed on the surface of breast cancer cells. Mannose triflate molecule is used as a precursor for synthesis of 18F-FDG by nucleophilic fluorination. For the conjugation of 18F-FDG and AuNPs, cysteamine was first bound to mannose triflate (Man-CA) before synthesizing of 18F-FDG which has cysteamine sides ( 18FDG-CA). Then, 18FDG-CA was reacted with HAuCl 4 to obtain AuNPs and with NaBH 4 for reduction of AuNPs. At the end of this procedure, AuNPs were conjugated to 18F-FDG via disulphide bonds ( 18FDG-AuNP). For the conjugation of Anti-MTDH, 1,1′-carbonyl diimidazol (CDI) was bound to the 18FDG-AuNP, and Anti-MTDH was conjugated via CDI ( 18FDG-AuNP-Anti-MTDH). This procedure was also performed by using Na 19F to obtain non-radioactive conjugates ( 19FDG-AuNP-Anti-MTDH). Scanning electron microscopy (SEM) images demonstrated that synthesized particles were in nano sizes. 18FDG-AuNP-Anti-MTDH conjugate was characterized and used as a model probe containing both radioactive and optical labels together as well as the biological target. The 18FDG-AuNP-Anti-MTDH conjugate was applied to MCF7 breast cancer cell line and apoptotic cell ratio was found to be increasing from 2% to 20% following the treatment. Hence, these results have promised an important application potential of this conjugate in cancer research.

Mutifuntional GdPO4:Eu3+ Hollow Spheres: Synthesis and Magnetic and Luminescent Properties

Mondispersed submicrometer GdPO(4):Eu(3+) hollow spheres were synthesized via an effective one-pot hydrothermal process. These hollow spheres have the average diameter of 200 nm, and the shell thickness is about 20 nm. The surface of the spheres consists of a number of nanorods with diameters of about 10 nm and lengths of about 50-80 nm. Both magnetic and luminescent properties of the obtained Eu(3+)-doped GdPO(4) hollow spheres were investigated. The hysteresis plot (M-H) analysis result indicates their paramagnetic property. The fluorescence spectra demonstrate that they emit orange-red color light originated from the (5)D(0) → (7)F(J) transitions of the Eu(3+) ions. Therefore, the obtained GdPO(4) hollow spheres hold promise for encapsulate drugs with controlled release. Moreover, the GdPO(4):Eu(3+) hollow spheres are attributes for bimodal magnetic resonance imaging (MRI)/optical bioimaging labeling.

Performance analysis of multiple optical orthogonal codes sequences–based optical labels for optical packet switching networks

Multiple optical orthogonal codes sequences (MOOCS)-based optical labels for optical packet switching (MOOCS-OPS) were proposed and studied in our previous works. In order to evaluate the performances of the MOOCS-OPS networks resulting from interference of the MOOCS-based optical labels, we utilize a new study method that applies the independent case of multiple optical orthogonal codes to derive the probability function of the MOOCS-OPS networks for the first time. Additionally, the optical label processing time, the utilization efficiency, and the packet loss rate in the MOOCS-OPS networks are also considered. We discuss the performance and efficiency characteristics with a variety of parameters, and compare some characteristics of the system employed by a single optical orthogonal code or MOOCS-based optical labels. The performances of the system are also calculated, and our results verify that the method and the networks are effective. Moreover, it is found that performances of the MOOCS-OPS networks would, negatively, be worsened, compared with the single optical orthogonal code-based optical label for optical packet switching; however, the MOOCS-OPS networks can greatly enlarge the scalability of the optical packet switching networks.

Optical Serial-to-Parallel Conversion Technique With Phase-Shifted Preamble for Optical Label Switching Systems

We have investigated the fundamental operation of optical serial-to-parallel converter (OSPC) scheme with phase-shifted preamble, and its application to optical label switching operation. The OSPC consists of a π/2 phase-shifted preamble at the top of the packet generated at a transmitter-side, and a -π/2 phase-biased Mach-Zehnder delayed interferometer with the delay length of the timing position of the gated bit followed by a balanced photodetector at a receiver-side. Firstly, we simulated the fundamental performance of the OSPC. The possibility of the serial-to-parallel operation was confirmed. The operation tolerance against the optical phase discrepancy from the ideal conditions, waveguide loss, extinction ratio, and chirp of the input signal were considered. Then, OSPC operation was experimentally investigated. 4-bit operation could be achieved with a suppression ratio of 8 dB in case of the input signal extinction ratio of 13 dB. For the purpose of verifying if the OSPC worked stably and if it could apply to optical label switching systems, packet transfer operation at a bit rate of 40 Gb/s with 2-bit label was also investigated, and we achieved error-free performance successfully for the first time.

All-optical recognition method of double two-dimensional optical orthogonal codes-based labels using four-wave mixing

A novel all-optical label recognition method is proposed and demonstrated experimentally which is based on fiber Bragg gratings (FBGs)-based encoder/decoder and semiconductor optical amplifier (SOA). In this scheme, the optical label is firstly decoded properly, the decoded signal then generates the 1st and the 2nd order four-wave mixing (FWM) effect in different SOA, any of the frequencies achieved by the 2nd order FWM is extracted to recognize the optical label. The proposed solution can favor hardware simplicity over bandwidth efficiency in order to achieve the double two-dimensional optical orthogonal codes (2D-OOCs)-based optical label recognition in an optical packet switching (OPS) system where the bandwidth efficiency can be improved by FWM effect in SOA to achieve optical label processing and reasonable spacing of wavelengths for the payloads and optical label. The feasibility of the proposed method is validated by two experiments of the double 2D-OOCs-based optical label generation and recognition, the effect of the optical label on the payloads is also considered. These results show that the proposed method can (1) reduce effectively the code auto-correlation /cross-correlation requirements of the optical label identification and remove the cross-correlation pulses after optical decoding, (2) increase greatly the coding capacity and the number of the available optical labels, (3) improve the reliability and bandwidth efficiency of the optical label identification. The experimental results also show that the optical label has a high extinction ratio and can be operated easily.