A simplified optoelectronic 3R regenerator without electrical signal processing is demonstrated by utilizing the nonlinear electro-optical transfer function of an electroabsorption modulator. 3R regeneration of impaired 10-Gb/s RZ signals is demonstrated, verifying the proposed concept.

We report on the first 40-Gb/s-based 160-Gb/s add-drop multiplexer (ADM) using a pair of standing-wave enhanced electroabsorption modulator (EAM). Direct time-domain switching is performed without interferometers or optical control pulses as required by previously reported approaches, which indicates great advantages in compactness for the EAM-based ADM. Also, a 40-Gb/s base rate is attractive in realizing a more efficient 160-Gb/s system. Error-free operation for all channels is obtained with an average power penalty as low as 1 dB.

We describe the design and performance of a number of elements based on traveling-wave electroabsorption modulators (TW-EAMs) in optical time-division-multiplexing (OTDM) and wavelength-division-multiplexing (WDM) networks. The incorporation of traveling-wave (TW) electrode design into electroabsorption modulators (EAMs) relieves the resistance-capacitance (RC) bandwidth limitation common to lumped components,. enabling higher operation speed without shortening the device. As a result, high-speed operation can be combined with essential modulator characteristics such as modulation efficiency and extinction ratio. While significant modulation bandwidth has been achieved, a lesser known aspect is that the TW electrode also provides an extra dimension for improving and enabling functionalities beyond broadband modulation. This new dimension originates from the distributed effect of the TW design and its interactions with distinctive EAM properties. This paper reviews such developments in recent years with specific applications for optical signal processing in OTDM and WDM networks. The covered functionalities include various optical gating operations for OTDM, regenerative wavelength conversions for WDM, and clock recovery.

Compact, 40-GHz: optical pulse generators are crucial to the implementation of practical 160-Gb/s optical time-division-multiplexing systems with 40-Gb/s. electrical time-division-multiplexing tributaries. In this letter, we report on a novel standing-wave enhanced mode of the electroabsorption modulator (EAM) which can improve the performance of a single EAM for 40-GHz pulse generation. Both experimental and theoretical results indicate that the distributed effect plays an important role in the high-frequency operation of the EAM and the length of the microwave termination line must be adjusted properly to maximize the performance.

Direct 160-10-Gb/s demultiplexing using a single-stage electrically gated electroabsorption modulator is reported for the first time. The drive signal consists of two mixed microwave tones used to reduce the gating window width to under 5.7 ps for both TE and TM modes. Error-free operation is obtained without an observed error floor. This single-stage design is compared to a dual-stage demultiplexer (160-40 and 40-10 Gb/s) and experimental results show that the power penalty is lower for the single-stage demultiplexer,illustrating both the performance and complexity advantages of the new design.

A novel Dynamically Reconfigurable Optical Packet Switch ( DROPS) that combines both spectral and spatial switching capabilities is proposed and experimentally demonstrated for the first time. Compared with an Arrayed Waveguide Grating Router ( AWGR), the added spatial switching capability provided by the microelectromechanical systems ( MEMS) enables dynamically reconfigurable routing that is not possible with an AWGR alone. This methodology has several advantages over an AWGR including scalability, additional degrees of freedom in routing a packet from an ingress port to an egress port and more flexibility in path or line card recovery. The experimental demonstration implemented with 10Gb/s packets shows that the added spatial switching does not degrade the bit-error-rate performance, indicating the promising potential of DROPS as a versatile and ultra-high capacity switch for optical packet-switched networks. (c) 2006 Optical Society of America.

A new mechanism of cross-absorption modulation is proposed and experimentally demonstrated to assist wavelength conversion using a traveling-wave electroabsorption modulator (TW-EAM). The photocurrent signal generated by the pump propagates along the TW electrodes and changes the absorption of the waveguide, which imprints data to the probe. The photocurrent signal can also be received by an external electronic circuit to provide monitoring capability. This photocurrent-assisted mechanism does not rely on the saturation of absorption and has the potential to reduce the high pumping power required by EAM-based wavelength converters. Using 2.5-Gb/s nonreturn-to-zero data, the conversion range can cover 30 nm in C-band and the lowest power penalty is 0.5 dB.

A traveling-wave electroabsorption modulator (TW-EAM) is used to realize three simultaneous functions: demultiplexing, detection, and pulse generation. These coexisting functions are achieved by utilizing microwave harmonic frequencies and independent wavelengths in the TW-EAM. When combined with a phase-locked-loop, these functions enable simultaneous optical demultiplexing, electrical clock recovery, and optical clock generation at line-rates of 40 and 160-Gb/s.

Low power penalty 80 to 10 Gbit/s demultiplexing using a novel standing-wave enhanced electroabsorption modulator is reported. In this new design, an electrical standing-wave pattern is formed deliberately along the travelling-wave electrodes, reducing the driving voltage required for high-speed demultiplexing.

Optical packet switching promises to bring the flexibility and efficiency of the Internet to transparent optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gb/s to beyond 40 Gb/s. In this article we review these signal processing techniques and how all-optical wavelength converter technology can be used to implement packet switching functions. Specific approaches that utilize ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results presented.