Combining advanced gaze tracking systems with the latest vehicle environment sensors opens up new fields of applications for driver assistance. Gaze tracking enables researchers to determine the location of a fixation, and under consideration of the visual saliency of the scene, to predict visual perception of objects. The perceptual limits, for stimulus identification, found in literature have mostly been determined in laboratory conditions using isolated stimuli, with a fixed gaze point, on a single screen with limited coverage of the field of view.
View Article and Find Full Text PDFThe increasing employment of eye-tracking technology in different application areas and in vision research has led to an increased need to measure fast eye-movement events. Whereas the cost of commercial high-speed eye trackers (above 300 Hz) is usually in the tens of thousands of EUR, to date, only a small number of studies have proposed low-cost solutions. Existing low-cost solutions however, focus solely on lower frame rates (up to 120 Hz) that might suffice for basic eye tracking, leaving a gap when it comes to the investigation of high-speed saccadic eye movements.
View Article and Find Full Text PDFFor optical communications links where receivers are signal-power-starved, such as through free-space, it is important to design transmitters and receivers that can operate as close as practically possible to theoretical limits. A total system penalty is typically assessed in terms of how far the end-to-end bit-error rate (BER) is from these limits. It is desirable, but usually difficult, to determine the division of this penalty between the transmitter and receiver.
View Article and Find Full Text PDFSpace-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity.
View Article and Find Full Text PDFWe propose and demonstrate silicon photonic integrated circuits (PICs) for free-space spatial-division-multiplexing (SDM) optical transmission with multiplexed orbital angular momentum (OAM) states over a topological charge range of -2 to +2. The silicon PIC fabricated using a CMOS-compatible process exploits tunable-phase arrayed waveguides with vertical grating couplers to achieve space division multiplexing and demultiplexing. The experimental results utilizing two silicon PICs achieve SDM mux/demux bit-error-rate performance for 1‑b/s/Hz, 10-Gb/s binary phase shifted keying (BPSK) data and 2-b/s/Hz, 20-Gb/s quadrature phase shifted keying (QPSK) data for individual and two simultaneous OAM states.
View Article and Find Full Text PDFThis Letter demonstrates a measurement technique based on frequency-to-time mapping and coherent detection, which enables the complete (i.e., amplitude and phase) characterization of dynamically reconfigurable photonic filters.
View Article and Find Full Text PDFWhile flexible bandwidth elastic optical networking is a promising direction for future networks, the spectral fragmentation problem in such a network inevitably raises the blocking probability and significantly degrades network performance. This paper addresses the spectral defragmentation problem using an auxiliary graph based approach, which transforms the problem into a matter of finding the maximum independent set (MIS) in the constructed auxiliary graph. The enabling technologies and defragmentation-capable node architectures, together with heuristic defragmentation algorithms are proposed and evaluated.
View Article and Find Full Text PDFWe demonstrate a flexible-bandwidth network testbed with a real-time, adaptive control plane that adjusts modulation format and spectrum-positioning to maintain quality of service (QoS) and high spectral efficiency. Here, low-speed supervisory channels and field-programmable gate arrays (FPGAs) enabled real-time impairment detection of high-speed flexible bandwidth channels (flexpaths). Using premeasured correlation data between the supervisory channel quality of transmission (QoT) and flexpath QoT, the control plane adapted flexpath spectral efficiency and spectral location based on link quality.
View Article and Find Full Text PDFWe demonstrate an optical transmitter based on dynamic optical arbitrary waveform generation (OAWG) which is capable of creating high-bandwidth (THz) data waveforms in any modulation format using the parallel synthesis of multiple coherent spectral slices. As an initial demonstration, the transmitter uses only 5.5 GHz of electrical bandwidth and two 10-GHz-wide spectral slices to create 100-ns duration, 20-GHz optical waveforms in various modulation formats including differential phase-shift keying (DPSK), quaternary phase-shift keying (QPSK), and eight phase-shift keying (8PSK) with only changes in software.
View Article and Find Full Text PDFWe experimentally demonstrate a dynamic line-by-line optical arbitrary waveform generation technique capable of generating continuous and bandwidth scalable high-fidelity waveforms without update rate limitations. Two quadrature modulators are used to create up to three spectral slices that are coherently combined by a passband-shaped multiplexer into a single contiguous spectrum to form complex optical waveforms with up to 30 GHz of bandwidth and 6 ns record lengths.
View Article and Find Full Text PDFThis paper presents the concept of an optical transmitter based on optical arbitrary waveform generation (OAWG) capable of synthesizing Tb/s optical signals of arbitrary modulation format. Experimental and theoretical demonstrations in this paper include generation of data packet waveforms focusing on (a) achieving high spectral efficiencies in quadrature phase-shift keying (QPSK) and 16 quadrature amplitude modulation (16QAM) modulation formats, (b) generation of complex data waveform packets used for optical-label switching (OLS) consisting of a data payload and label on a carrier and subcarrier, and (c) repeatability and accuracy of duobinary (DB) data packet waveforms with BER measurements. These initial demonstrations are based on static OAWG, or line-by-line pulse shaping, to generate repeated waveforms of arbitrary shape.
View Article and Find Full Text PDFWe demonstrate a high-performance optical arbitrary waveform shaper based on a single 10 GHz arrayed-waveguide grating with 64 loopback waveguides and integrated amplitude and phase modulators on each waveguide. The design is compact and self-aligning and allows for bidirectional operation. The device's complex transfer function is manipulated and measured over the full 640 GHz passband.
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