Over the last decade, significant progress has been made in the development of Terahertz (THz) imagers to satisfy the growing interest for see-through devices for different market applications. The noise-equivalent power (NEP) is a widely accepted figure of merit used to compare the sensitivity performance of detectors. However, with no widely recognized standard for NEP, it is often difficult to have a fair comparison between different sensors. Having a clear understanding of the characterization method used to calculate this important metric will lead to better estimation of the performances that could be expected from an imaging device. There is some confusion regarding whether NEP should be expressed in terms of power (W) or power by spectral density (W/Hz1/2). The difference between the two expressions is the normalization of the first by the square root of the detector’s equivalent noise bandwidth (ENBW). By properly defining the ENBW for a specific sensor, the translation between the two is then consistent. This paper presents the NEP characterization of INO’s Microxcam-384i camera over a wide frequency range. A description of the measurement setup is provided, as well as the details of the analysis method, including the estimation of the ENBW. Finally, values for the NEP using both expressions are provided for wavelengths between 70μm (4.5 THz) and 1.5mm (198 GHz), demonstrating the broadband sensitivity of the camera.
Materials for three dimensional optical memories have been the focus of significant research. The development of appropriate optical addressing technologies have been cited as critical to the practical exploitation of the potential density and throughput achievable in three dimensional optical memory architectures. Coherent optical arrays have been cited as an undeveloped but potentially groundbreaking component in the optical addressing of three dimensional memories. Designs and simulations for PLZT based single and multiple lobe optical phased arrays are presented. These PLZT based optical phased array structures implement optical scanners and scanning optical array generators. The physical structure of the devices can be varied to allow operation at a specific optical wavelength and optical beam resolution. The integrated optical scanners and scanning optical array generators can be implemented with simple three-port voltage dividers and dc current drivers. These devices could provide the geometric reconfiguration of optical pathways required of addressing schemes in three dimensional optical memory architectures.
A 2D optoelectronic diffraction grating based on PLZT ceramic material for optical switching and reconfigurable optical interconnect applications is demonstrated. Integrable chips are fabricated consisting of numerous fine interleaved transparent indium-tin oxide electrodes on a polycrystalline PLZT ceramic substrate. The chips measure one centimeter square. Electrode features are scales and measure from 12.5 micrometers to 100 micrometers . Reported here are chip material and fabrication details.
A preliminary design is presented for an Optical Interface Message Processor (OPTIMP) which exploits the high bandwidth, parallelism, multidimensional capability, and high storage density offered by optics. In the proposed system, the time-consuming operations in parallel processing networks, such as switching and routing, are fully implemented in optics. The design is free from optical/electrical conversion bottlenecks and can perform switching and routing in the Gigabits/s range. The design can be adapted for interconnection networks for massively parallel computers.
A switching technique using the polarization sensitivity of photorefractive holograms in crystals is experimentally demonstrated. The design is capable of handling a large number of 2 X 2 switching channels with only four holograms. The concept is applicable to either synchronous or asynchronous switching and also to a variety of photorefractive materials.
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