Nobuyuki Kataoka

Characterization of a full encoder/decoder in the AWG configuration for code-based photonic Routers-part II: experiments and applications

A 200-gigachip/s multiple encoder/decoder in an arrayed waveguide configuration, which generates and recognizes simultaneously 16 optical labels in parallel, has been fabricated. The device has been experimentally characterized, and a 10-Gb/s 50-km optical packet switching (OPS) experiment has been successfully performed: Optical packets are switched to their own destinations using a single device with a processing rate of 13 gigapackets/s.

Generation of Versatile Waveforms From CW Light Using a Dual-Drive Mach-Zehnder Modulator and Employing Chromatic Dispersion

In this paper, we analyze waveform generation using a single-stage dual-drive Mach-Zehnder modulator and a dispersive fiber. We derive a mathematical expression for the waveform generation process in the time domain and use this to propose a waveform generation algorithm. Furthermore, versatile waveforms, such as short pulse, trapezoidal, triangular and sawtooth waveforms and doublet pulse, are theoretically generated under different combinations of the four variables. The generated waveforms are analyzed in terms of the gradient and the instantaneous frequency. Finally, the waveform generation is experimentally demonstrated at the repetition rate of 10 GHz.

Field Trial of Duplex, 10 Gbps

An optical code-division multiple access (OCDMA) over wavelength-division multiplexing (WDM) system could be one promising solution to the symmetric gigabit access network with high spectral efficiency, cost effective, good flexibility and enhanced security. A cost-effective OCDMA/WDM system using a single multi-port en/decoder at an optical line terminal (OLT) and superstructured fiber Bragg grating (SSFBG) encoder/decoders at each optical network unit (ONU) in an optical network has been proposed and demonstrated. In this paper, we prepare 16-chip, 16-level phase-shifted SSFBG encoder/decoders and develop the full-asynchronous 10 Gigabit Ethernet (10 GbE) interface OCDMA prototype for the first time. Field trials of duplex, fully-asynchronous, 10 Gbps times 8-user DPSK-OCDMA system over 100 km using hybrid multi-port and SSFBG encoder/decoder are demonstrated.

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A 200 Gchip/s, 16-label simultaneous multiple-optical encoder/decoder has been fabricated; it generates and recognizes simultaneously multiple codes in a parallel manner. 10 Gbit/s optical packet switching with the test encoder/decoder was demonstrated experimentally. Optical packets with different labels were switched according to their own destination label based on multiple label processing.

8-User DPSK-OCDMA System Using a Single 16

Security enhancement of stealth channel by combining time-domain spectral phase en/decoding (SPE/D) OCDMA scheme and group velocity dispersion is proposed and experimentally demonstrated. The time-domain spectral phase encoded OCDMA signal, which utilizes a linearly chirped fiber Bragg grating for pulse broadening and a high-speed phase modulator for SPE, has been stealth transmitted over a public wavelengthdivision-multiplexing network. Error-free transmission (bit-error rate <; 10-9) has been achieved for both the public and stealth channel with 32-chip 40-Gchip/s gold codes.

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We propose and experimentally demonstrate a time-domain bit-by-bit code-shifting scheme that can rapidly program ultralong, code-length variable optical code by using only a dispersive element and a high-speed phase modulator for improving information security. The proposed scheme operates in the bit overlap regime and could eliminate the vulnerability of extracting the code by analyzing the fine structure of the time-domain spectral phase encoded signal. It is also intrinsically immune to eavesdropping via conventional power detection and differential-phase-shift-keying (DPSK) demodulation attacks. With this scheme, 10 Gbits/s of return-to-zero-DPSK data secured by bit-by-bit code shifting using up to 1024 chip optical code patterns have been transmitted over 49 km error free. The proposed scheme exhibits the potential for high-data-rate secure optical communication and to realize even one time pad.

16 Multi-Port Encoder/Decoder and 16-Level Phase-Shifted SSFBG Encoder/Decoders

We developed a new 8-chip, 320 Gchip/s multi-port encoder/decoder for 40-Gbps PON networks. Asynchronous, 40-Gbps × 4-user DPSK-OCDMA transmission over 50 km has been successfully demonstrated for the first time.

200 Gchip/s, 16-label simultaneous multiple-optical encoder/decoder and its application to optical packet switching

Reconfigurable optical add/drop multiplexers (ROADMs), which enable dynamic and flexible node-to-node connection via wavelength paths, are key components in metro ring network nodes. A data-granularity-flexible ROADM node that combines a wavelength-tunable filter, and an optical packet ADM (PADM) has been proposed and demonstrated. In this paper, the first field trial of the data-granularity-flexible ROADM network with wavelength- and packet-selective switch is demonstrated using a novel concurrent generation technique of address-reconfigurable optical-code (OC) labels and payload data. Bit error rates (BERs) of less than 10/sup -12/ for all 16-wavelength channels are obtained over 90 km of transmission at 10 Gb/s.

Stealth Transmission of Time-Domain Spectral Phase Encoded OCDMA Signal Over WDM Network

A novel scheme using single phase modulator for simultaneous time domain spectral phase encoding (SPE) signal generation and DPSK data modulation is proposed and experimentally demonstrated. Array- Waveguide-Grating and Variable-Bandwidth-Spectrum-Shaper based devices can be used for decoding the signal directly in spectral domain. The effects of fiber dispersion, light pulse width and timing error on the coding performance have been investigated by simulation and verified in experiment. In the experiment, SPE signal with 8-chip, 20GHz/chip optical code patterns has been generated and modulated with 2.5 Gbps DPSK data using single modulator. Transmission of the 2.5 Gbps data over 34km fiber with BER<10(-9) has been demonstrated successfully. The proposed scheme has simple configuration and improved flexibility that can significantly improve the data confidentiality for optical code division multiple access (OCDMA) and secure optical communication applications.

Rapid programmable/code-length-variable, time-domain bit-by-bit code shifting for high-speed secure optical communication

Reconfigurable optical add/drop multiplexers (ROADMs) are able to provide flexible wavelength path provisioning in wavelength division multiplexing (WDM) networks. However, the capability of conventional ROADMs is limited to handling wavelength paths, and it does not support fine granularity in add/drop multiplexing of packets. Recently, we have proposed and demonstrated a packet-selective ROADM that combines an acoustooptic wavelength-tunable filter (AOTF) and an optical packet ADM (PADM) using optical code label processing. It provides more efficient utilization of wavelengths than conventional ROADMs. However, the bit rate of the demonstration was limited up to 10 Gbit/s. In this paper, we newly develop a label-selectivity-enhanced optical en/decoder, which allows the optical label recognition with 40-Gbit/s nonreturn-to-zero (NRZ) data packets, and a wide pass-band AOTF for 40-Gbit/s signals. Furthermore, we develop 640-Gbit/s throughput, packet-selective ROADM prototype, and demonstrate a field trial of granularity-flexible 3-node optical network over 173 km. error-free packet ADMs (error rate of under 10-12) for all 16-wavelength channels at all nodes are obtained.