Passive Optical Communications Module for the Internet of Things

The Internet of Things (IoT) promotes interconnectivity between devices and these keep appearing in larger quantities throughout the years, with the evolution of communication technologies. However, scalability comes with a price, since for a higher quantity of devices comes the need for better transmission channels, with higher reach, availability and improved security capabilities. The infrastructure that comes with this ubiquitous network is very expensive so there is a need for finding low-cost solutions for the transmission of data, benefiting from the qualities of the optical fibers.Wireless technologies already provide a way to solve these issues, but the use of optical fibers would give to the IoT their own unique features, such as high bandwidth, long reach, signal integrity and high security. But IoT devices should not be power hungry nor have very limiting electrical-to-optical conversions, so a passive optical communications module based of fiber Bragg gratings for long reach and for the upload of information with low data rates should be implemented. This module would be integrated in the IoT ecosystem by connecting it to the existent dark fibers all over the world.A simulator of this module was implemented, capable of reproducing its characteristics for the transmission of information modulated in Frequency-Shift Keying and On-Off Keying modulation schemes. The study of the system performance for these schemes was made by estimating the Bit Error Rate using the Error Vector Magnitude metric, in relation to the received optical power

Semiconductor-based all-optical switching for optical time-division multiplexed networks

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references.All-optical switching will likely be required for future optical networks operating at data rates which exceed electronic processing speeds. Switches utilizing nonlinearities in semiconductor optical amplifiers (SOA) are particularly attractive due to their compact size, low required switching energies, and high potential for integration. In this dissertation we investigate the practical application of such semiconductor-based all-optical switches in next-generation optical networks. We present both theoretical and experimental studies of SOA-based interferometric switches. A detailed numerical model for the dynamic response of an SOA to an intensity-modulated optical signal is described. The model is validated using novel pump-probe techniques to measure the time-domain response of an SOA subject to various levels of saturation. The model is then used to evaluate the performance of three common SOA-based interferometric all-optical switches. The use of SOAs in optical transmission systems has been limited due to the deleterious effects of pattern-dependent gain saturation. We develop a statistical model to study the system impact of variations of the SOA optical gain in response to a random intensity-modulated optical signal. We propose the use of pulse-position modulation (PPM) as a means for mitigating gain saturation effects in SOA-based optical processors. We present techniques for modulation and detection of optical PPM signals at data rates in excess of 100 Gbit/s. We demonstrate demultiplexing, wavelength conversion, and format conversion of optical PPM signals at data rates as high as 80 Gbit/s. Finally, we report on experimental demonstrations of an optical interface for slotted OTDM networks.(cont.) We implement head-end and transmitter nodes capable of producing fully loaded optical slots at an aggregate network data rate of 112.5 Gbit/s. We demonstrate a fully functional receiver node which utilizes semiconductor-based all-optical logic for synchronization, address processing, and rate conversion.by Bryan S. Robinson.Ph.D