We review recent advances in distributed fiber optic sensing (DFOS) and their applications. The scattering mechanisms in glass, which are exploited for reflectometry-based DFOS, are Rayleigh, Brillouin, and Raman scatterings. These are sensitive to either strain and/or temperature, allowing optical fiber cables to monitor their ambient environment in addition to their conventional role as a medium for telecommunications. Recently, DFOS leveraged technologies developed for telecommunications, such as coherent detection, digital signal processing, coding, and spatial/frequency diversity, to achieve improved performance in terms of measurand resolution, reach, spatial resolution, and bandwidth. We review the theory and architecture of commonly used DFOS methods. We provide recent experimental and field trial results where DFOS was used in wide-ranging applications, such as geohazard monitoring, seismic monitoring, traffic monitoring, and infrastructure health monitoring. Events of interest often have unique signatures either in the spatial, temporal, frequency, or wavenumber domains. Based on the temperature and strain raw data obtained from DFOS, downstream postprocessing allows the detection, classification, and localization of events. Combining DFOS with machine learning methods, it is possible to realize complete sensor systems that are compact, low cost, and can operate in harsh environments and difficult-to-access locations, facilitating increased public safety and smarter cities.

Employing RF sub-band multiplexing with the aid of ultra-wide band RF IQ mixers, we demonstrated a 200G DP-QPSK transmitter using two RF sub-bands and a single optical carrier. The novel technique is readily applicable to current commercial coherent DSP designed for 100G without the need for high baud-rate generation electrically. The 200G DP-QPSK transmitter, implemented using the fabricated ultra-wide band mixers, was shown to have great OSNR tolerance as it suffers only 0.5~1-dB OSNR penalty when compared to a standard 100G Nyquist DP-QPSK transmitter. The proposed RF sub-banding architecture could potentially reduce the cost and power consumption at the transmitter side for coherent optics design, without suffering the transmission penalty associated with high baud-rate generation and/or complex modulation format.

As 100-Gb/s digital coherent systems enter commercial deployment, an effort is underway to uncover the technologies that will enable the next-generation optical fiber communication systems. We envisage that future optical transport will be software-defined, enabling flexible allocation of bandwidth resources, with dynamically adjustable per-channel data rates based on instantaneous traffic demand and quality-of-service requirements, leading to unprecedented network agility. Software-defined transponders will have the programmability to adopt various modulation formats, coding rates, and the signal bandwidth based on the transmission distance and type of fiber. Digital signal processing will become increasingly ubiquitous and sophisticated, capable of compensating all types of channel impairments, enabling advanced forward error correction coding, and performing functions previously handled poorly by optical analog hardware such as spectrum shaping and demultiplexing of optical channels.

As microprocessors become increasingly interconnected, the power consumed by the interconnection network can no longer be ignored. Moreover, with demand for link bandwidth increasing, optical links are replacing electrical links in inter-chassis and inter-board environments. As a result, the power dissipation of optical links is becoming as critical as their speed. In this paper, we first explore options for building high speed optoelectronic links and discuss the power characteristics of different link components. Then, we propose circuit and network mechanisms that can realize power-aware optical links -links whose power consumption can be tuned dynamically in response to changes in network traffic. Finally, we incorporate power control policies along with the power characterization of link circuitry into a detailed network simulator to evaluate the performance cost and power savings of building power aware optoelectronic networked systems. Simulation results show that more than 75% savings in power consumption can be achieved with the proposed power aware optoelectronic network.

To recognize and understand a person’s emotion has been known as one of the most important issue in human-computer interaction. In this paper, we present a multimodal system that supports emotion recognition from both visual and acoustic feature analysis. Our main achievement is that with this bimodal method, we can effectively extend the recognized emotion categories compared to when only visual or acoustic feature analysis works alone. We also show that by carefully cooperating bimodal features, the recognition precision of each emotion category will exceed the limit set up by the single modality, both visual and acoustic. Moreover, we believe our system is closer to real human perception and experience and hence will make emotion recognition closer to practical application in the future.