Device Cross Research Articles

Push-pull microring-assisted space-and-wavelength selective switch.

We introduce a novel design of a space-and-wavelength selective switch based on microring-assisted Mach-Zehnder interferometers. Multiple pairs of overcoupled microring resonators are incorporated as efficient and narrowband phase shifters and are driven in push-pull scheme. We design and demonstrate a 2×2×2λ elementary switch block with full spatial and spectral switching capabilities. The switching device's cross talk suppression and extinction ratio both exceed 21 dB. We measure over 75 GHz optical bandwidth per channel and less than 1.5 dB power penalty at 10-9 BER when two 32 Gbps on-off keying signals are loaded simultaneously. This new class of switching elements can further enable compact and high-performance space-and-wavelength selective switch fabrics without the need for wavelength (de)multiplexers or parallel switching planes.

Angular dependence of DRAM upset susceptibility and implications for testing and analysis

Heavy ion irradiations of two types of commercial DRAM's reveal unexpected angular responses. One device's cross section varied by two orders of magnitude with azimuthal angle. Accurate prediction of space rates requires accommodating this effect.

An Effect of Instrument Attachment on Foraging Trip Duration in Chinstrap Penguins

The behavior of seabirds away from the breeding colony is poorly understood. Recently, however, technologies have become available that promise to greatly expand our knowledge of the activity of birds at sea. Specifically, recent technological developments have led to studies of seabird diving (see Kooyman 1989), nest attendance (Wanless et al. 1985), foraging range and dive durations (Trivelpiece et al. 1986, Wanless et al. 1988a, Bengtson and Eberhardt 1989), and swimming velocity (Wilson and Bain 1984). These studies have relied upon electronic devices attached to the animal in some manner. Although essential in helping researchers to understand the activities of seabirds away from the nest, attached devices have the potential to alter the behavior of the animal under study either through the effects of increased drag or through the discomfort of instrument package attachment. This problem has recently been recognized by a number of investigators: (1) Wilson et al. (1986) found that velocity meters attached to African Penguins (Spheniscus demersus) decreased swimming velocity (inversely related to the device's cross sectional area), and potentially decreased net foraging trip energy gain. (2) Wanless et al. (1988b) found that Common Murres (Uria aalge) fitted with radio transmitters with external antennas spent less time in the colony, were absent for long periods, and delivered fewer prey to their young. (3) Wilson et al. (1989) found that the handling and trimming of tail feathers of Adelie Penguins (Pygoscelis adeliae) increased the duration of a single foraging trip, and the attachment of devices increased nest desertion and foraging trip duration (after 19 days of attachment). They also speculated that the diving depths of penguins may be affected by recorder attachment, with mean maximum depths decreasing with increasing device cross-sectional area. (4) Wilson and Bain (1984) found that African Penguins peck at devices when researchers are out of the sight of the birds, while Adelie Penguins may spend a considerable amount of time trying to remove a device (Wilson et al. 1990). Thus, studies of the effects of instruments on seabird behavior and performance are essential in interpreting results obtained by using them. The purpose of this study was to examine the potential effects of attaching radio transmitters and time-depth recorders (TDRs) on the foraging trip durations of Chinstrap Penguins breeding on Seal Island, South Shetland Islands, Antarctica.