The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We demonstrate multi-level optical weights embedded in a silicon photonic platform based on ferroelectric domain switching. Ferroelectric barium titanate integrated on silicon resonator structures is used as the memory material. By applying short voltage pulses of 100ns, we can switch fractions of the ferroelectric domains and thus change the transmission of the waveguides by more than one order of...
The rapidly changing RF landscape creates a requirement for flexible frequency access as well as the ability to move signals over long distances. This paper presents the characterization and experiments of a wide band photonics enabled transceiver. The architecture, SFDR, noise figure, and gain are presented, followed by the results of communications experiments involving up to 25 km of remoting fiber...
Orthogonal frequency-division multiplexing (OFDM) is employed extensively in wireless communication networks to reduce receiver side computational complexity, improve tolerance to fading, improve spectral efficiency, and ease synchronization; it is also being considered for 5G systems [1]. Traditionally, communication links operate with shared knowledge of modulation parameters, here we focus on developing...
Broadband wireless transmission with tunable 5–40GHz carrier is demonstrated using photonic frequency conversion. The agile tuner allows ∼4 GHz of instantaneous bandwidth for both up- and down-conversion paths, without banding or channelization.
Demonstration of low conversion loss through the novel integration and packaging of high power photodiodes and a fragmented aperture antenna for a fiber-fed RF array.
Integration of UVA-developed high power photodiodes into a novel RF package co-designed with a wide-bandwidth, fragmented aperture antenna for fiber-fed, array antenna applications.
We investigate compressibility of the dimension of positive semidefinite matrices while approximately preserving their pairwise inner products. This can either be regarded as compression of positive semidefinite factorizations of nonnegative matrices or (if the matrices are subject to additional normalization constraints) as compression of quantum models. We derive both lower and upper bounds on compressibility...
Photonic components and technologies enable complimentary capability to enhance traditional RF and digital EW jammer system architectures. A trade study between RF and photonic architectures is performed to address switch matrix design for EW applications.
Photonic components and technologies augment and enhance traditional RF and digital EW jammer system architectures. Four identified capabilities enabled by photonics are simultaneous transmit and receive, frequency conversion, true-time delay, and photodiode/antenna integration.
A concept for the architecture of optical local area networks for aerospace applications has been established by a team of engineers representing several organizations within the aerospace industry. The concept has been derived using sound systems engineering principles, and uses Wavelength Division Multiplexing (WDM) to greatly increase data transmission capacity. Interoperability for the purpose...
We demonstrate Offset-QPSK transmitter and receiver architectures for 112 Gb/s coherent optical networks, highlighting similarities and differences to QPSK implementations. Experimentally we demonstrate that O-QPSK exhibits an enhanced immunity to nonlinearities when transmitted over TrueWave® fiber links.
Offset QPSK is a linear modulation format exhibiting nearly constant envelop and hence may avoid nonlinear refraction effects and thus enable higher launch power and a commensurate increase in reach. We experimentally demonstrate >2dB advantage for OQPSK compared to QPSK for multi span coherent optical links using TrueWave® RS fiber.
The ovary is a female organthat houses a fixed supply of germ cells (oocytes). The absolute number of oocytes at any given stage can be a useful indicator of fertility. Obtaining accurate assessments of the oocyte reserve in humans and experimental models can be time consuming and error prone. In this paper a new approach to facilitate oocyte counting in microscope images of mouse ovariesis presented...
Predicated execution has been used to reduce the number of branch mispredictions by eliminating hard-to-predict branches. However, the additional instruction overhead and additional data dependencies due to predicated execution sometimes offset the performance advantage of having fewer mispredictions. We propose a mechanism in which the compiler generates code that can be executed either as predicated...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.