122,341 research outputs found
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No full textIn order to obtain an N X N Multistage Interconnection Network capable of passing all the N supplementary stages must be added to the standard ones. In this paper we prove that the completeness property of such networks is preserved even if some switching element suffers from a stuck-at fault. The critical stage is the central one which must be set in a fixed configuration, depending on the desired permutation. This problem is easily overcome if one additional stage is included. Moreover, the static full access capability is preserved in a complete network because of the redundancy of source to destination paths
Photonic waveguiding array Sensor for measuring amplitude and Phase of High-Frequency E-Fields
No full textModeling of guided-wave acousto-optic multifrequency interaction in Bragg regime
No full textIn this work the modeling of non collinear acoustooptic multifrequency interaction in wave- guiding structures is presented. The new model, which is based on the generalized coupled mode theory, allows us to evaluate the diffraction efficiency in Bragg regime when a multifrequency signal is applied to the interdigitated transducer deposited on the optical waveguide surface. The dependence of diffraction efficiency of the output orders on the intermodulation factors and on the transducer driving radiofrequencies has been investigated. The influence of fabrication parameters of Ti:LiNbO3 waveguides on the linear dynamic range of acoustooptic multifrequency modulators has been extensively studied under monomodal propagation condition. Our results assert that the best performance in terms of linear dynamic range (approximately equals 43 dB) can be obtained on Ti:LiNbO3 waveguides having weak refractive index change ((Delta) n < 0.001), small initial titanium thickness (< 100 angstroms) and medium enter radiofrequency (approximately equals 500 MHz)
Modelling and design of a highly sensitive integrated optical sensor of microwave E-fields
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No full textIn this work the modeling of multifrequency acoustooptic interaction in guiding structure is presented. This model, based on a generalized coupled mode theory, allows us to evaluate the Bragg diffraction efficiency when a multifrequency signal is applied to the interdigited transducer. The dependence of diffraction efficiency of the output orders and of the intermodulation factors among the same orders on both the applied voltage amplitudes and transducer driving radiofrequencies has been extensively investigated. Planar waveguide structures on lithium niobate have been considered under monomodal propagation condition
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No full textIn this paper we present the theoretical study and design of a GaAs-based guided-wave grating device for uniform out-coupling of optical power, to be detected on an external 2D plane. The model of diffraction is based on the exact solution of the relevant boundary-value problem. The device is formed by a number of cascaded gratings, each of them having different geometric characteristics. Simulations have been carried out at different values of grating thickness and number of cascaded gratings, in order to obtain the best performance in terms of diffraction efficiency and device transmissivity. Uniform distribution of the out-coupled power on a 2D region has been achieved by varying the groove depth of each cascaded gratings. This device can be successfully used to obtain uniform illumination of coupled-charge-devices in optical computing and signal processing applications, such as image restoring in synthetic aperture radar systems, spectral analysis, matrical multiplication, and so on
Performance limits of guided-wave devices for space applications
No full textn this paper some significant developments of guided-wave devices and recent technological advances in optoelectronics for space are described. The performance limits of these devices are highlight in terms of technological problems, power consumption, operating frequency, sizes and weight
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No full textIn this work are presented the design parameters and performance of a guided-wave spectrum analyzer based on a multilayered ZnO/AlxGa1-xAs/AlyGa1-yAs/GaAs structure for heterodyne detection of spread spectrum signals. The adopted circuit configuration includes a double integrated collimating grating having non linear groove profiles, an acousto-optic Bragg cell, a concave frating lens, a focusing grating lens and an output photodiode array. The optical structure has been optimized as a function of the layer thickness, and Al title in order to obtain improved performance of the circuit in terms of 3-dB Bragg bandwidth (up to 185 MHz), surface acoustic wave power consumption (less than 3 mW), frequency resolution (less than 1.5 MHz), and single-tone dynamic range (about 56 dB). The number of channels has been found equal to 112 and 125 in the two structures under investigation, respectively. The calculated single- and double-tone dynamic range are reduced of about 40% with respect to the corresponding dynamic ranges of the homodyne architecture. All the design parameters have been calculated for each integrated component of the circuit at the free-space optical wavelength of 0.85 micrometers
A method to classify neutrino events according to their completeness
No full textComplete neutrino events are separated from the total sample with a discriminant analysis in a many-dimensional space described in the text. Two new powerful variables are found which discriminate with high efficiency and tag the event type as far as the completeness is concerned
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