John M. Garcia

An Integrated Hybrid Silicon Multiwavelength AWG Laser

The first integrated multiwavelength laser based on an arrayed waveguide grating (AWG) fabricated on a silicon-on-insulator wafer is presented. It consists of Fabry-Perot cavities integrated with hybrid silicon amplifiers and an intracavity filter in the form of an AWG with a channel spacing of 360 GHz. Four-channel lasing operation is shown. Single-sided fiber-coupled output powers as high as 35 μW are measured. The device shows subnanosecond rise and fall times, and direct modulation at 1 GHz gives an open eye with an extinction ratio of 7.7 dB.

Integrated Photonics for Low-Power Packet Networking

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.

Cascadability properties of MZI-SOA-based all-optical 3R regenerators for RZ-DPSK signals

We experimentally demonstrate 50 cascaded all-optical 3R regenerators over a 1,000 km transmission distance for 10-Gb/s return-to-zero differential phase-shift keying (RZ-DPSK) signals. The regenerator consists of integrated Mach-Zehnder interferometer (MZI) semiconductor optical amplifier (SOA) based wavelength converters. Regenerative properties and tolerance to pattern dependent effects have been studied in terms of Q-factor measurement, and error free operation with input OSNR of 20 dB/0.1 nm has also been demonstrated.

All-optical 2R regeneration of BPSK and QPSK data using a 90° optical hybrid and integrated SOA-MZI wavelength converter pairs

We demonstrate all-optical 2R regeneration with a 90° optical hybrid and integrated MZI-SOA pairs for 10 Gb/s BPSK and 20 Gb/s QPSK with negative power penalty. Power penalty and OSNR improvements of 7 dB and 5 dB are shown with additive ASE noise.

Monolithically integrated dual-quadrature receiver on InP with 30 nm tunable local oscillator

We demonstrate a monolithically integrated dual-quadrature coherent receiver with greater than 30 nm widely-tunable SG-DBR local oscillator, signal input SOAs, a 90° optical hybrid and four 10 GHz photodetectors. With 20 Gb/s NRZ-QPSK, we demonstrate a required OSNR of 10 dB for a BER of 10(-3) at four different wavelengths.

Integrated recirculating optical hybrid silicon buffers

We present our work on fully integrated hybrid silicon optical buffers capable of holding 40 byte packets at 40 Gb/s. These devices consist of low loss silicon waveguides and cascaded amplifiers to overcome passive losses in a 1.1 m long delay line. Since cascading multiple gain elements leads to ASE (noise) accumulation, reshaping elements in the form of saturable absorbers are integrated in the delay. Noise filtering in the buffer is investigated by simulating the eye diagram for a delay line with 1R regenerators and comparing it to that of a 2R regenerator. Finally, preliminary experimental data from the optical buffer is shown.

25 Gbaud DQPSK receiver integrated on the hybrid silicon platform

A monolithic 25 Gbaud DQPSK receiver based on delay interferometers and balanced detection was fabricated on hybrid silicon platform. We report preliminary results regarding the characterization of the InGaAs p-i-n photodetectors and the delay interferometer.

A fully integrated hybrid silicon AWG based multiwavelength laser

For the first time, a fully integrated hybrid silicon AWG based multiwavelength laser on SOI is presented. Four-channel operation with 360 GHz spacing and 25–35 dB SMSR is shown.

Synchronous Optical Packet Buffers

Synchronous optical packet buffering is presented as a solution for asynchronous time division multiplexed (TDM) optical packet switched networks. Truly asynchronous optical packet synchronization and buffering are demonstrated using multiple independent transmitters, synchronous optical buffers, and a burst mode receiver. Optical packet synchronizers are used to dynamically align incoming asynchronous packets to local timeslots for synchronous loading of buffers. Multiple optical buffers based on integrated InP technology resolve contention of packets destined for the same output port at the same time. TDM asynchronous optical packets are detected on a per packet basis using a burst mode receiver with better than 99.9% packet recovery. An analysis of power consumption of the synchronous buffers is presented and potential power reductions are discussed.

End-to-end asynchronous optical packet transmission, scheduling, and buffering

The first demonstration of asynchronous optical packet transmission, scheduling, and buffering is presented using asynchronous/autonomous transmitters, lookup, buffer and a burst mode receiver. Contention resolution is shown with greater than 99.8% packet recovery at 10 Gb/s.