107-Gb/s Serial Optical Packet Switching With 1-bit/s/Hz Spectral Efficiency for 100-GbE Backplanes

We demonstrate 107-Gb/s optical packet switching using electronically multiplexed duobinary signals, fast tunable lasers, and a 40 times 40 arrayed waveguide grating router. With a spectral efficiency of 1 bit/s/Hz, the fabric scales to 4-Tb/s capacity and is suitable for 100-Gb Ethernet backplanes.     

Characterization of the Dynamic Absorption of Electroabsorption Modulators With Application to OTDM Demultiplexing

In this paper, a technique for characterizing the dynamic absorption of electroabsorption modulators (EAMs) under high-frequency sinusoidal modulation is described. By using an optical sampling oscilloscope (OSO), the nonlinear response of a modulator to 10- and 40-GHz modulation is accurately measured. The results for the dynamic absorption are used in a measurement-based model to calculate optical gating windows for the demultiplexing of a 160-Gb/s optical time-division multiplexed (OTDM) signal to its 10- and 40-Gb/s tributary signals. Good agreement is achieved between the calculated and measured gating windows.      

100-Gb/s Packet Signal Generation With Spectral Efficiency Larger Than 1 bit/Hz/s

We have experimentally demonstrated how to generate 100-Gb/s packet signals with spectral efficiency higher than 1bit/Hz/s for the first time. The optical packet with 3.125-Gb/s label and 100-Gb/s return-to-zero differential quadrature phase-shift-keying payload are generated by using optical carrier-suppression and separation and vestigial sideband filtering techniques. The performance of transmission and label erasure has also been evaluated.     

On-the-Fly All-Optical Contention Resolution for NRZ and RZ Data Formats Using Packet Envelope Detection and Integrated Optical Switches

We present a packet-by-packet contention resolution scheme that combines packet detection, optical space switching, and wavelength conversion performed in the optical domain by integrated optical switches. The packet detection circuit provides the control signals required to deflect and wavelength-convert the contending packets so that all the packets are forwarded to the same output without any collision or packet droppings. We demonstrate the compatibility of the scheme with both nonreturn-to-zero (NRZ) and return-to-zero (RZ) modulation formats by recording error-free operation for 10-Gb/s NRZ and 40-Gb/s RZ packet-mode traffic     

A novel scheme for generating optical dark return-to-zero pulses and its application in a label switching optical network

We experimentally demonstrate a novel and simple method to generate a dark return-to-zero (RZ) pulse with tunable pulsewidth and extinction ratio by using a dual-arm LiNbO /sub 3/ intensity modulator. Our experimental results show that this dark RZ pulse signal can be used in a 10-Gb/s optical packet switching system as an optical label. In addition, we demonstrate that this dark RZ label can be easily erased using the gain saturation effect in a semiconductor optical amplifier.     

WDM PON using 10-Gb/s DPSK downstream and re-modulated 10-Gb/s OOK upstream based on SOA

A signal remodulation scheme of 10-Gb/s differential phase-shift keying(DPSK) downstream and 10-Gb/s on-off keying(OOK) upstream using a semiconductor optical amplifier(SOA) and a Mach-Zehnder intensity modulator(MZ-IM) at the optical networking unit(ONU) side for wavelength division multiplexed passive optical network(WDM PON) is proposed.Simulation results indicate that error-free operation can be achieved in a 20-km transmission,and the receiver sensitivity of return-to-zero differential phase-shift keying(RZ-DPSK) is higher than nonreturn-to-zero differential phase-shift keying(NRZ-DPSK) in the proposed scheme.     

Optical demultiplexing at 6 Gb/s using a semiconductor laser amplifier as an optical gate

A semiconductor laser amplifier (SLA) has been employed successfully for optical demultiplexing in two-channel optical time division multiplexed system experiments at 6 and 2 Gb/s. Demultiplexing of 6-Gb/s (2-Gb/s) signals was demonstrated with a power penalty of 1.6 dB (3.0 dB) at bit error rates of 10/sup -9/. It is also shown that a reduction of the generated amplified spontaneous emission can be obtained by optical gating/demultiplexing for systems incorporating inline amplifiers. A 0.5-dB improvement in sensitivity was achieved as a result of using an SLA for demultiplexing from 2.0 to 1.0 Gb/s in a system with one inline Er/sup 3+/-doped fiber amplifier.<>     

Optical Packet-Switched Network Employing Optically Labeled 114-Gb/s RZ-8PSK Packet Signals Through Straight-Line Optical Wavelength-Selective Switching Nodes

We experimentally show the first demonstration of optically labeled 100-Gb/s packet polarization-multiplexing signals passing through four optical wavelength-selective switching (OWSS) nodes. In this architecture, the payload is generated by polarization-multiplexing return-to-zero octaphase-shift-keying format at 114 Gb/s, and 2.5-Gb/s on–off keying signal is used for the carrying label. By using the vestigial sideband filtering, the spectra efficiency is increased up to 1 b/Hz/s. The bit-error-rate performance for both payload and label are evaluated after passing through four straight-line OWSS nodes in this optical network.      

All-optical network subsystems using integrated SOA-based optical gates and flip-flops for label-swapped networks

In this letter, we demonstrate that all-optical network subsystems, offering intelligence in the optical layer, can be constructed by functional integration of integrated all-optical logic gates and flip-flops. In this context, we show 10-Gb/s all-optical 2-bit label address recognition by interconnecting two optical gates that perform xor operation on incoming optical labels. We also demonstrate 40-Gb/s all-optical wavelength-switching through an optically controlled wavelength converter, consisting of an integrated flip-flop prototype device driven by an integrated optical gate. The system-level advantages of these all-optical subsystems combined with their realization with compact integrated devices, suggest that they are strong candidates for future packet/label switched optical networks.     

Rayleigh Backscattering Noise-Eliminated 115-km Long-Reach Bidirectional Centralized WDM-PON With 10-Gb/s DPSK Downstream and Remodulated 2.5-Gb/s OCS-SCM Upstream Signal

We propose a novel scheme of Rayleigh backscattering noise-eliminated, long-reach, single-fiber, full-duplex, centralized wavelength-division multiplexed passive optical network with differential quadrature phase-shift keying (DPSK) downstream and remodulated upstream using an optical carrier-suppressed subcarrier-modulation (OCS-SCM) technique and optical interleaver. The error-free transmissions of 10-Gb/s downstream and 2.5-Gb/s upstream signals are experimentally demonstrated over 115-km single-fiber bidirectional SMF-28 with less than 0.5 and 1.9 dB power penalties, respectively.      

40-Gb/s OTDM to 4×10 Gb/s WDM conversion in monolithic InPMach-Zehnder interferometer module

Transformation of high bit-rate optical time-domain multiplexed (OTDM) signals into a multitude of lower bit-rate wavelength-division-multiplexed (WDM) channels is demonstrated by means of a single monolithically integrated indium phosphide Mach-Zehnder interferometer with semiconductor optical amplifiers in its arms. Full demultiplexing of 10-Gb/s OTDM signals into 4×10-Gb/s WDM channels is demonstrated. Bit-error-rate penalties are below 1.5 dB for polarization independent signal conversion throughout the 1.55-μm wavelength range     

A wavelength-tunable semiconductor amplifier/filter for add/drop multiplexing in WDM networks

Reconfigurable channel drop in a wavelength-division multiplexed system is demonstrated using a packaged semiconductor amplifier/filter. The filter is electrically tunable over 9.0 nm with a 0.9-nm width and is used with an optical circulator to demultiplex three 5.0-Gb/s WDM channels spaced by 2.25 nm. A receiver sensitivity improvement and low optical crosstalk is observed over a dynamic range of nearly 10 dB.     

A novel transmitter architecture for combined baseband data and subcarrier-multiplexed control links using differential Mach-Zehnder external modulators

We propose, analyze, and demonstrate a novel transmitter architecture for links that support transmission of base-band data and subcarrier multiplexed control channels. The architecture utilizes a differential external integrated-optic modulator to electrooptically combine the base-band and subcarrier multiplexed data onto an optical carrier. An analytical model is presented that allows optimization of the SNR of the received base-band and control data channels based on modulation parameters. This optimization is based on tradeoffs that result when the base-band and subcarrier channel are combined using a nonlinear modulator transfer function. We experimentally demonstrate a link based on this architecture with 2.5-Gb/s base-band and 100-Mb/s control data multiplexed on a 5.5-GHz subcarrier. Analytical and measured experimental results are compared and are shown to be in good agreement.     

Wavelength Conversion Based on Copolarized Pumps Generated by Optical Carrier Suppression

Polarization-insensitive wavelength conversion based on four-wave mixing for 112-Gb/s polarization- multiplexed return-to-zero quadrature phase-shift keying signals (PolMux-RZ-QPSK) with digital coherent detection is experimentally demonstrated. The dual-pumps always have the same polarization direction and fixed frequency spacing because they are generated by the optical carrier suppression technique. The conversion efficiency at different pumping powers and signal wavelengths has also been investigated. A tuning range of a signal wavelength of wider than 18 nm is realized with the same conversion efficiency in this proposed architecture. There is no obvious optical signal-to-noise ratio penalty for the converted 112-Gb/s PolMux-RZ-QPSK signals.      

Semiconductor laser diode optical amplifiers/gates in photonicpacket switching

In this paper, we will describe how semiconductor laser diode optical amplifiers/gates can be used in the photonic packet switching systems based on wavelength division multiplexed (WDM) techniques. First, we show that cross-gain modulation (XGM) can be suppressed when the device is used in the transparent condition of the waveguide material even when the input signal power exceeds +18 dBm. We then discuss an appropriate encoding for the optical signal. Experimental results show that high bit rate Manchester-encoding enables the use of semiconductor laser diode optical amplifiers/gates in the gain condition as well as the transparent condition. Finally, a new photonic packet receiver which utilizes a semiconductor laser diode optical amplifier as a packet power equalizer is proposed. This receiver accepts 17 dB power fluctuation at nanosecond speed for 10 Gb/s Manchester-encoded signal     

Duty-ratio control of nonlinear phase noise in dispersion-managed WDM transmissions using RZ-DPSK modulation at 10 Gb/s

The authors compare analytical and numerical estimates, showing that the nonlinear phase noise of short optical pulses associated with the coupling between amplified spontaneous emission noise and fiber nonlinearity may be controlled by adjusting the duty cycle of the return-to-zero (RZ) signal modulation format. The impact of this effect in the optimization of the performance of 10-Gb/s dispersion-managed wavelength division multiplexed (WDM) systems using RZ-differential phase-shift keying (DPSK) modulation is discussed. By extensive numerical simulations, it is shown that the transmission quality of ultradense WDM systems using the RZ-DPSK modulation format may be significantly enhanced by optimizing the duty cycle of the RZ pulses.     

Optical clock-pulse-train generator for processing preamble-free asynchronous optical packets

An optical clock-pulse-train generator (OCPTG) for processing asynchronous arbitrary-length optical packets with no preamble is developed. The OCPTG consists of a fiber-loop-based optical pulse-train generator (PTG) and an optical clock-pulse generator that, for every input asynchronous optical packet, generates a single, synchronized optical pulse which is fed to the PTG. Generation of an optical clock-pulse-train with stable pulse energy, precise repetition rate, and duration matching the input packet is achieved for variable-length optical packets. The OCPTG and an all-optical demultiplexer combined demonstrate error-free demultiplexing of a 10-Gb/s asynchronous optical packet stream.     

Sensitivity improvement of a 2 Gb/s quadrature phase shift keyedsubcarrier multiplexed system by use of an optical preamplifier

A traveling wave semiconductor optical amplifier is used as a receiver preamplifier in a quadrature-phase-shift-keyed subcarrier multiplexed system. The intensity-modulated signal from a 1509-m distributed feedback laser bears two 1-Gb/s data signals on a 5-GHz subcarrier. The receiver preamplifier yields a 9.2-dB sensitivity improvement to -29.2 dBm. The system noise sources are measured. Theoretical and measured bit error rates versus received power are presented     

Ultrafast all-optical pattern matching using differential spin excitation and its application to bypass/drop self-routing for asynchronous optical packets

This paper presents a novel scheme for ultrafast all-optical pattern matching using the differential spin excitation in semiconductor multiple quantum wells (MQWs). In a demonstration of an all-optical pattern matching between two 100-Gb/s 16-bit optical packets, the contrast ratio of the photodiode (PD) output from the pattern matcher, between the pattern matched and the pattern-unmatched cases, was more than four for packets with a 2-dB power fluctuation. As an application of the pattern matcher to optical-packet-switched ring networks, bypass/drop self-routing is demonstrated for asynchronous 100-Gb/s 32-bit optical packets with 8-bit labels. In the experiment, a label of an incoming packet was compared to a local address (LA) given to a node in the optical domain. By changing the pattern of the LA packet instead of that of the incoming packet, the pattern matching was carried out for packets with various kinds of patterns. The contrast ratio of the PD output was more than six for all patterns.     

In-Band OSNR Monitoring Using Spectral Analysis After Frequency Down-Conversion

A novel method for simultaneous optical signal-to-noise ratio and chromatic dispersion monitoring in wavelength-division multiplexed 40-Gb/s systems is proposed and demonstrated. This technique has a fast response time of <10 ms, applicable to dynamically reconfigurable networks, and is able to simultaneously monitor multiple impairments across multiple channels