Cédric Ware

640-Gbit/s Data Transmission and Clock Recovery Using an Ultrafast Periodically Poled Lithium Niobate Device

This paper presents the first demonstration of the use of a periodically poled lithium niobate device for signal processing at 640 Gbit/s. Clock recovery is performed successfully using the lithium niobate device, and the clock signal is used to control a nonlinear fiber-based demultiplexer. The full 640-Gbit/s system gives error-free performance with no pattern dependence and there is less than 1-dB power penalty after 50-km fiber transmission.

Radio-Over-Fiber Access Network Architecture Based on New Optimized RSOA Devices With Large Modulation Bandwidth and High Linearity

Next-generation wireless communications systems need to have high throughputs to satisfy user demand, to be low-cost, and to have an efficient management as principal features. Using a high-performance, low-cost reflective semiconductor optical amplifier (RSOA) as a colorless remote modulator at the antenna unit, the wavelength-division multiplexing (WDM) technique can be used for supporting distributed antenna systems (DASs). Each antenna unit is connected to the central unit using optical fiber and all links are used to transmit radio signals. Due to a large optical bandwidth, RSOAs are potential candidates for cost effective WDM systems. In this paper, simulations are carried out to determine optimized RSOA devices for wireless technology. New RSOA structures are fabricated and evaluated. The optimized RSOA is electrically driven by a standard Wi-Fi input signal (IEEE 802.11 g) with a 64-quadrature amplitude modulation (QAM) format. A large modulation bandwidth and a high electrooptic gain are demonstrated, which are confirmed by good performance when using orthogonal frequency-division multiplexing techniques. Characteristics such as high linearity and large electrooptic modulation bandwidth of our RSOA are sufficient to ensure an error vector magnitude (EVM) lower than 5% with a dynamic range exceeding 35 dB in a back-to-back configuration (at 0 dBm). Uplink transmission over a 20 km of single-mode fiber is also demonstrated with EVM lower than 5% and a dynamic range exceeding 25 dB (at 5 dBm).

10-GHz clock recovery using an optoelectronic phase-locked loop based on three-wave mixing in periodically poled lithium niobate

Clock recovery is a critical function of any digital communications system. To replace the classical electronic phase-locked loops (PLLs) at higher bit rates, several all-optical or optoelectronic clock recovery methods are being studied. This letter presents an optoelectronic PLL where three-wave mixing in a periodically poled lithium niobate (PPLN) device provides the phase comparator. Since PPLN is passive, it generates no amplified spontaneous emission noise; also, the error signal is in the visible (763 nm), therefore easily separated from infrared input signals. Clock recovery is performed on a 10-GHz sinusoidal optical signal. Being based on ultrafast nonlinear effects, this scheme should be able to reach still higher bit rates, on the order of several hundred gigahertz. Also, subclock extraction (e.g., 40-to-10 GHz) should be possible without modifications.

320 Gbps to 10 GHz sub-clock recovery using a PPLN-based opto-electronic phase-locked loop

We present successful extraction of a 10 GHz clock from single-wavelength 160 and 320 Gbps OTDM data streams, using an opto-electronic phase-locked loop based on three-wave mixing in periodically-poled lithium niobate as a phase comparator.

All-Optical Packet-Switching Decoder Design and Demonstration at 10 Gb/s

A 3 times 8 all-optical decoder based on cross-polarization modulation in semiconductor optical amplifiers is demonstrated for the first time to our knowledge. The design requires a single active optical device per output. Experimental results are shown for return-to-zero modulated 10-Gb/s signals. Applications include label processing in optical packet switched optical networks

650 Gbit/s OTDM transmission over 80 km SSMF incorporating clock recovery, channel identification and demultiplexing in a polarisation insensitive receiver

Error free low penalty 650 Gbit/s OTDM transmission is demonstrated using a polarisation independent receiver based on FWM for demultiplexing. Spectral shaping in the transmitter and filtering in the receiver are used for clock extraction.

Nonlinear Pulse Reshaping With Highly Birefringent Photonic Crystal Fiber for OCDMA Receivers

We combine an erbium-doped fiber amplifier with a short segment of highly birefringent photonic crystal fiber to generate a nonlinear transfer function suitable for optical transmission systems based on optical code-division multiple-access (OCDMA). Such a functional element based on spectral broadening followed by an off-center narrow optical filtering provides an effective suppression of spurious signals such as multiple-access interferences in OCDMA receivers and can reduce the pulses amplitude jitter.

Optical-Logic-Gate Aided Packet-Switching in Transparent Optical Networks

The objective of this research is to propose two new optical procedures for packet routing and forwarding in the framework of transparent optical networks. The single-wavelength label-recognition and packet-forwarding unit, which represents the central physical constituent of the switching node, is fully described in both cases. The first architecture is a hybrid opto-electronic structure relying on an optical serial-to- parallel converter designed to slow down the label processing. The remaining switching operations are done electronically. The routing system remains transparent for the packet payloads. The second architecture is an all-optical architecture and is based on the implementation of all-optical decoding of the parallelized label. The packet-forwarding operations are done optically. The major subsystems required in both of the proposed architectures are described on the basis of nonlinear effects in semiconductor optical amplifiers. The experimental results are compatible with the integration of the whole architecture. Those subsystems are a 4-bit time-to-wavelength converter, a pulse extraction circuit, a an optical wavelength generator, a 3times8 all-optical decoder and a packet envelope detector.

Optical Packet Header Processing Using Time-to-Wavelength Mapping in Semiconductor Optical Amplifiers

A new approach for optical packet header processing based on a time-to-wavelength converter is proposed. The processing is composed of transferring, through an all-optical and-gate, the header data bits into the successive single optical pulses at different wavelengths. The and-gate is performed by the semiconductor optical amplifier (SOA) and makes use of either cross-polarization modulation or four-wave mixing (FWM). Both implementations are compared. In order to improve the scalability of the design and to overcome the polarization sensitivity of the FWM solution, we propose the use of a spectrum-sliced incoherent light in generating the wavelength bits. The FWM process in this specific case is studied. The 10-Gb/s demonstrations of the various elements are presented.

30 GHz sub-clock recovery using an opto-electronic phase-locked loop based on four-wave mixing in a semiconductor optical amplifier

Clock recovery is an important function of any digital communications system, critical for receiving and possibly regenerating the signal. For higher bit rates, it has been proposed to use an opto-electronic PLL, in which the up-front mixer or phase comparator is replaced by a semiconductor optical amplifier (SOA): the nonlinearities of this device, e.g. four-wave mixing (FWM), act as a mixer, not only in the optical-frequency domain but also in the modulation-frequency domain; and its time-response characteristics act as a NRZ-to-pseudo-RZ converter. Such a system, akin to a simple PLL in which FWM in a SOA replaces the high-frequency mixer, had been demonstrated for 10 Gbps RZ and NRZ signals.