9 research outputs found
Vertical cavity surface emitting laser based optoelectronic asynchronous transfer mode switch
Abstract. Large broadband asynchronous transfer mode (ATM) switching nodes require novel hardware solutions that could benefit from the inclusion of optical interconnect technology, since electronic solutions are limited by pin out and by the capacitance/inductance of the interconnections. We propose, analyze and demonstrate a new three stage free space optical switch that utilizes vertical cavity surface emitting lasers (VCSELs) for the optical interconnections, a liquid crystal spatial light modulator (SLM) as a reconfigurable shutter and relatively simple optics for fan out and fan in. A custom complementary metal oxide semiconductor (CMOS) chip is required to introduce a time delay in the optical bit stream and to drive the VCSELs. Analysis shows that the switch should be scalable to 1024ϫ1024, which would require 2048 ϳ2 mW VCSELs
Comparison of the CKLL first-derivative Auger spectra from XPS and AES using diamond, graphite, SiC and diamond-like-carbon films
Thermal Resistance of VCSEL's Bonded to Integrated Circuits
Abstract-The thermal resistance of vertical-cavity surfaceemitting lasers (VCSEL's) flip chip bonded to GaAs substrates and CMOS integrated circuits has been measured. The measurements on GaAs show that if the bonding is done properly, the bonding does not add significantly to the thermal resistance. However, the SiO 2 under the CMOS bonding pad can double the thermal resistance unless measures are taken to improve the thermal conductance of these layers. Finite element simulations indicate that the thermal resistance of bonded VCSEL's increases rapidly as the solder bond size and the aperture size decrease below 10 m
The natives in their places: “Ethnographic cartography”; and the representation of autonomous spaces in Ovamboland, German South West Africa
Making Maps That Matter: Situating GIS within Community Conversations about Changing Landscapes
Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies
Flare frequency distributions represent a key approach to addressing one of
the largest problems in solar and stellar physics: determining the mechanism
that counter-intuitively heats coronae to temperatures that are orders of
magnitude hotter than the corresponding photospheres. It is widely accepted
that the magnetic field is responsible for the heating, but there are two
competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To
date, neither can be directly observed. Nanoflares are, by definition,
extremely small, but their aggregate energy release could represent a
substantial heating mechanism, presuming they are sufficiently abundant. One
way to test this presumption is via the flare frequency distribution, which
describes how often flares of various energies occur. If the slope of the power
law fitting the flare frequency distribution is above a critical threshold,
as established in prior literature, then there should be a
sufficient abundance of nanoflares to explain coronal heating. We performed
600 case studies of solar flares, made possible by an unprecedented number
of data analysts via three semesters of an undergraduate physics laboratory
course. This allowed us to include two crucial, but nontrivial, analysis
methods: pre-flare baseline subtraction and computation of the flare energy,
which requires determining flare start and stop times. We aggregated the
results of these analyses into a statistical study to determine that . This is below the critical threshold, suggesting that Alfv\'en
waves are an important driver of coronal heating.Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The
Astrophysical Journal on 2023-05-09, volume 948, page 7