Milan L. Mašanović

All-optical label swapping networks and technologies

All-optical label swapping is a promising approach to ultra-high packet-rate routing and forwarding directly in the optical layer. In this paper, we review results of the DARPA Next Generation Internet program in all-optical label swapping at University of California at Santa Barbara (UCSB). We describe the overall network approach to encapsulate packets with optical labels and process forwarding and routing functions independent of packer bit rate and format. Various approaches to label coding using serial and subcarrier multiplexing addressing and the associated techniques for label erasure and rewriting, packet regeneration and packet-rate wavelength conversion are reviewed. These functions have been implemented using both fiber and semiconductor-based technologies and the ongoing effort at UCSB to integrate these functions is reported. We described experimental results for various components and label swapping functions and demonstration of 40 Gb/s optical label swapping. The advantages and disadvantages of using the various coding techniques and implementation technologies are discussed.

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In this paper, we demonstrate single-channel operation of the first InP monolithic tunable optical router (MOTOR) chip designed to function as the packet forwarding engine of an all-optical router. The device has eight-input and eight-output ports and is capable of 40-Gb/s operation per port with bit-error rates below 1E-9. MOTOR integrates eight wavelength-tunable differential Mach-Zehnder semiconductor optical amplifier (SOA) wavelength converters with preamplifiers and a passive 8 × 8 arrayed-waveguide grating router. Each wavelength converter employs a widely tunable sampled-grating distributed Bragg reflector (DBR) laser for efficient wavelength switching across the C band and other functions required for 40-Gb/s wavelength conversion. Active and passive regions of the chip are defined through a robust quantum well intermixing process to optimize the gain in the wavelength converters and minimize the propagation losses in passive sections of the chip. The device is one of the most complex photonic integrated circuits (PICs) reported to date, with dimensions of 4.25 mm × 14.5 mm and more than 200 functional elements integrated on-chip. We demonstrate single-channel wavelength conversion and channel switching with this device using 231 - 1 pseudorandom bit sequence (PRBS) data at 40 Gb/s. A power penalty as low as 4.5 dB was achieved with less than 2-W drive power per channel.

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As the demand for bandwidth increases, the communications industry is faced with a paradigm shift. Photonic integration is a key technology that will facilitate this shift. Monolithic integration allows for the realization of highly functional optical components, called photonic integrated circuits. Herein, we discuss the advantages and potential applications of photonic integration, and after a brief overview of various integration techniques, provide a detailed look at our work using a novel quantum well intermixing processing platform.

8 InP Monolithic Tunable Optical Router (MOTOR) Packet Forwarding Chip

Design, fabrication, and characterization of monolithically integrated widely tunable all-optical wavelength converters in InP is reported. The devices are based on the SGDBR laser integrated with different MZI-SOA wavelength converters. Error-free wavelength conversion at 2.5 Gbps was demonstrated over 50 nm input and 22 nm output wavelength range. Static operation, extinction ratio enhancement, signal reamplification, dynamic range, and chirp properties were characterized as well.

Monolithically integrated active components: a quantum-well intermixing approach

The first integrated sampled-grating distributed Bragg reflector (SGDBR) laser-semiconductor optical amplifier-Mach-Zehnder modulator transmitter is presented. Devices have 3 dB bandwidth ranging from 13-18 GHz corresponding to electrodes lengths that range between 200-300 /spl mu/m long. This corresponds to a V/sub pi/ of 4.8-6.2 V.

Widely tunable monolithically integrated all-optical wavelength converters in InP

This paper describes the design and demonstration of advanced 40-Gb/s return-to-zero (RZ) tunable all-optical wavelength converter technologies for use in packet-switched optical networks. The device designs are based on monolithic integration of a delayed interference Mach-Zehnder interferometer (MZI) semiconductor optical amplifier (SOA) wavelength converter with a sampled-grating distributed Bragg reflector tunable laser and an on-chip waveguide delay. Experimental results are presented demonstrating error-free wavelength conversion with 1-dB power penalty at 40-Gb/s data rates. By incorporating label modulation functionality on-chip along with a fast tunable 40-Gb/s wavelength converter, fully monolithic packet-forwarding chips are realized that are capable of simultaneous error-free wavelength conversion of 40-Gb/s payloads, remodulation of 10-Gb/s packet headers, and data routing through fast wavelength switching

A widely tunable high-speed transmitter using an integrated SGDBR laser-semiconductor optical amplifier and Mach-Zehnder modulator

The first monolithically integrated widely tunable wavelength converter, consisting of a sampled-grating distributed-Bragg-reflector laser (SGDBR) and an SOA-based Mach-Zehnder interferometer, is reported. The integration process requires only a single regrowth step. Static extinction ratios (electrical/optical) better than 18 dB and 13 dB, respectively, were measured over a 22-nm wavelength tuning range. Digital wavelength conversion at bit rate of 2.5 Gb/s was demonstrated to be error free, with 2.6-dB power penalty.

Monolithic Wavelength Converters for High-Speed Packet-Switched Optical Networks

We demonstrate the first InP monolithic tunable optical router with error-free 40 Gbps operation per port. The device has eight wavelength converters and an 8×8 arrayed-waveguide grating router, yielding more than 200 on-chip functional elements.

Monolithically integrated Mach-Zehnder interferometer wavelength converter and widely tunable laser in InP

We report on a new widely tunable all-optical wavelength converter consisting of a sampled-grating distributed Bragg reflector (SGDBR) laser monolithically integrated with a Mach-Zehnder interferometer semiconductor optical amplifier (MZI-SOA)-based wavelength converter. The new design incorporates independent phase control of the interferometer and SOAs for amplification of the SGDBR output. For the first time, error-free operation for data rates of up to 10 Gb/s is reported for 35-nm output tuning range. The high-speed operation is enabled by high photon density in the SOA due to large power transfer from the on-board tunable laser and amplifiers. We also report on device sensitivity of -10 dBm at 2.5 Gb/s and -5 dBm at 10 Gb/s, with an average output power of 0 dBm.

The world's first InP 8×8 monolithic tunable optical router (MOTOR) operating at 40 Gbps line rate per port

Communications interconnects and networks will continue to play a large role in contributing to the global carbon footprint, especially in data center and cloud-computing applications exponential growth in capacity. Key to maximizing the benefits of photonics technology is highly functional, lower power, and large-scale photonics integration. In this paper, we report on the latest advances in the photonic integration technologies used for asynchronous optical packet switching using an example photonic integrated switched optical router, the label switched optical router architecture. We report measurements of the power consumed by the photonic circuits in performing their intended function, the electronics required to bias the photonics, processing electronics, and required cooling technology. Data is presented to show that there is room (potentially greater than 10 ×) for improvement in the router packet-forwarding plane. The purpose of this exercise is not to provide a comparison of all-optical versus electronic routers, rather to present a data point on actual measurements of the power contributions for various photonic integration technologies of an all-optical packet router that has been demonstrated and conclude, where the technology can move to reduce power consumption for high-capacity packet routing systems.