ABSTRACT
Following the lack of microscopic information about the intriguing well-known electrical-thermal switching mechanism in carbon-black-polymer composites, we applied atomic force microscopy in order to reveal the local nature of the process and correlated it with the characteristics of the widely used commercial switches. We conclude that the switching events take place in critical interparticle tunneling junctions that carry most of the current. The macroscopic switched state is then a result of a dynamic-stationary state of fast switching and slow reconnection of the corresponding junctions.
ABSTRACT
We describe a modified confocal microscope in which depth discrimination results from matched filtering by a volume hologram instead of a pinhole filter. The depth resolution depends on the numerical aperture of the objective lens and the thickness of the hologram, and the dynamic range is determined by the diffraction efficiency. We calculate the depth response of the volume holographic confocal microscope, verify it experimentally, and present the scanned image of a silicon wafer with microfabricated surface structures.
ABSTRACT
Electric-field multiplexing (EFM) results from the tuning of the effective wavelength of the light beam inside a photorefractive crystal. This tuning results from the application of an external electric field to the crystal during holographic recording. We demonstrate the high Bragg selectivity of this multiplexing technique in paraelectric crystals and compare it with the selectivity obtained in the ferroelectric phase. The effects of the two major physical parameters of working in the paraelectric phase, the temperature and the external electric field applied during the writing stage, are investigated. Experimental results of the EFM of three image-bearing holograms recorded in reflection geometry are presented along with a qualitative analysis of the Bragg selectivity in paraelectric crystals.
ABSTRACT
We describe a new approach for constructing large-scale artificial neural networks. The novelty of our approach is based on the concept of electroholography (EH), which permits interconnecting of electronic neurons by minute-volume holograms, using the voltage-controlled photorefractive effect in paraelectric crystals. Crystals of potassium lithium tantalate niobate (KLTN) in the paraelectric phase are shown to be suitable for implementing this concept. A small network composed of two KLTN crystals on which holographic connections are recorded is presented to demonstrate the EH approach.
