Dwight Richards

100-Gb/s PAM4 link modeling incorporating MPI

100-Gb/s PAM4 optical links based on cascaded silicon modulators and DSP-based receivers are comprehensively modeled. Simulation results highlight the impact of key impairments such as MPI, RIN, passive loss, and receiver noise.

LUCID: a visualization and broadcast system for cyber defense competitions

In this article, we discuss LUCID, a visualization and broadcast system targeted to improving a spectators ability to understand and make sense of cyber defense competitions. The system aims to engage the spectator by presenting information pertinent to understanding the real-time events of the competition as they unfold. It accomplishes this through a combination of techniques, including real-time network security visualization, live video and audio monitoring, animation, computer graphics, user profiling, and commentary. We examine, specifically, how the LUCID system enables the audience to make sense of ongoing activities in a cyber defense competition.

Performance modeling and analytical verification of POF transmissive star couplers for avionics system applications

We discuss the performance modeling of transmissive star couplers based on plastic optical fibers which are designed for avionics system applications. Simulation is based on a commercial software tool where the concept of supermodes is introduced. Results are validated using an analysis which expands on prior work based on multimode couplers in polymers.

Linear crosstalk analysis of an un-amplified ring PON architecture

Passive optical network (PON) architectures have been proposed as a back haul for wireless networks, where the optical network units (ONUs) can now be interconnected with the antenna base stations. We focus on a ring PON approach with its inherent benefits and use simulation to analyze the effects of linear crosstalk in an un-amplified basic TDM optical ring. Our approach is based on simulation of the entire network using a combination of wavelength-domain and time-domain techniques. Typically PON networks are based on CWDM to maintain the cost of components low and in such case it is logical that any crosstalk will be negligible. However, the subpar performance of such components motivated our study into the crosstalk impact. We show that the tap ratio optimization which increases the number ONUs that can be served in the ring can also exacerbate the effects of linear interchannel crosstalk at the ONUs downstream signal receivers. The interchannel crosstalk originates from the upstream/LAN transmission and is due to non-ideal WDM couplers/splitters and optical switches that are needed for wavelength multiplexing/demultiplexing and protection against node and link failures, respectively.

Improved tolerance to the combined effect of in-band crosstalk and chromatic dispersion in partial DPSK systems

We use simulations to investigate the influence of the value of the differential delay of the Mach-Zehnder interferometer (MZI) demodulator in differential phase-shift-keyed (DPSK) systems when the system is limited by the combined effect of chromatic dispersion and in-band crosstalk. It is found that the dispersion and filtering tolerance improvement which is realized when the delay is less than one bit-period is preserved in systems with strong in-band crosstalk.

Using system simulation to evaluate design choices for automotive ethernet over plastic optical fiber

The growing bandwidth demands of advanced driver assistance systems (ADAS) and infotainment technologies make Gigabit Ethernet over plastic optical fiber (POF) a natural choice for next-generation automotive data networks, especially in light of the recent approval of the IEEE 802.3bv standard for Gigabit Ethernet transmission over POF. POF-based transmission provides the advantages of low cost, light weight, easy termination, durability, and immunity to electromagnetic interference (EMI), while Gigabit Ethernet extends the current maximum data rate of 150 Mb/s provided by Media Oriented Systems Transport (MOST). Thus, we examine important design choices that impact the performance of POF-based automotive data links for data rates up to and beyond 1 Gb/s and different choices of modulation format, including NRZ and PAM-n. Because simulation is an efficient and cost-effective solution for studying the complex interplay of multiple design choices without requiring physical prototypes, we base our analysis on a comprehensive modeling framework for optical communication systems incorporating large-core step-index fiber and fiber-to-fiber connectors. We study anticipated system performance in terms of bandwidth and BER for different choices of link length and connector count, including the IEEE 802.3bv targets of 15 meters with four connectors and 40 meters with no connectors. In addition, we consider the impact of connector misalignments (both lateral and longitudinal) and source launch profile (measured in terms of its encircled angular flux, or EAF), which also directly affect link bandwidth.

Simulation of silicon photonic coherent PM-QPSK transceivers using microring modulators

Silicon photonic components are key enablers for low-cost, compact, and reduced power-consumption coherent transceivers. This paper discusses models used to analyze the performance of silicon photonic ring modulators in coherent links, and presents simulation results for 32- and 16-Gbaud PM-QPSK back-to-back transceivers incorporating these modulators in comparison with designs using LiNbO3 MZMs. While the penalty at 32 Gbaud is high, at 16 Gbaud the ring modulator performance approaches that of the MZM, with a sensitivity penalty of only 1.3 dB. Our results also show the strong temperature sensitivity of the ring modulator.

Optical network element simulation results for avionic WDM lans

We provide baseline simulation results for cascaded Optical Crossconnects (OXCs) in an avionic WDM LAN platform, taking into consideration effects of loss and amplification for each optical network element (ONE). The simulations are supported by measurements performed on a prototype test bed, and are extended to show the effect of cascaded ONEs, including use of Optical Amplifiers (OA) if needed. The presented simulation results for 2.5Gb/s and 10Gb/s digital signals will be used to define key interfaces and optical transfer functions for the SAE Internationals aircraft platform WDM LAN standards.

Crosstalk analysis of an extended reach hybrid tree-ring PON architecture

Passive optical network (PON) is the leading technology being used for delivering last-mile connectivity without any active components in the distribution network. In this paper, we focus on an un-amplified hybrid tree-ring PON architecture that carries the benefits of both the tree and the ring architectures. Through simulation, we demonstrate the optical performance of the system and focus on the physical layer performance impact of interchannel and intrachannel crosstalk due to non-ideal WDM multiplexers/demultiplexers and optical switches in the system.