Optical Arbitrary Waveform Generation and Measurement Transmission Systems and Its Application to Flexible Bandwidth Networking

Abstract

The exponentially increasing demand for Internet bandwidth demands a bandwidth scalable optical network infrastructure. Next-generation flexible-bandwidth networks expect to operate over a broad bandwidth using arbitrary bandwidth channels in arbitrary modulation formats. These dynamically reconfigurable networks rely on optical transceivers capable of providing an efficient match between allocated bandwidth and demand while maximizing the achievable spectral efficiency. Implementing flexible-bandwidth networking at the physical layer, however, requires a technique for overcoming the electronic bottleneck and exploiting photonic device technology to create a bandwidth scalable transmission system.

This dissertation focuses on the development of a flexible-bandwidth capable transmission system based on a dynamic optical arbitrary waveform generation (OAWG) and measurement (OAWM). Dynamic OAWG enables the generation of large bandwidth optical waveforms (>100-GHz) by coherently combining many lower bandwidth (<40-GHz) spectral slices together to form a contiguous bandwidth output. This technique operates by creating many spectral slices from a set of coherent comb lines using a parallel modulator structure. In a complementary fashion, OAWM allows for the measurement of large bandwidth optical signals by dividing a continuous spectrum into lower bandwidth (<40-GHz) spectral slices for parallel detection using a set of digital coherent receivers.

Experimental demonstrations verify the bandwidth scalability of the dynamic OAWG technique, and show its ability to generate modulated data waveforms in arbitrary modulation formats without time-duration limitations. Additionally, dynamic OAWG/OAWM transmission system demonstrations show operation using multiple arbitrary bandwidth channels in arbitrary modulation formats, including both single- and multi-carrier formats.

This work continues with flexible-bandwidth networking testbed demonstrations that leverage the versatility of an OAWG transmitter paired with an adaptive, real-time control plane to dynamically adjust the bandwidth allocation of the channels. In particular, this enables impairment awareness, in which adjusting the modulation format (i.e., bandwidth allocation) of a channel allows maintaining a desired bitrate under conditions of time-varying link impairments.

Finally, recent results highlight terahertz scale monolithic photonic devices for dynamic OAWG that combine spectral demultiplexers, modulators, and spectral multiplexers into a single device. Results include the characterization of 100-channel × 10-GHz OAWG devices that have over 1,200 active components.