In this work we have designed, fabricated, and tested a photonic crystal slab (PCS) with a line defect waveguide for the
detection and identification of pathogenic DNA. A PCS is constructed by fabricating a material with 2-dimensional
dielectric periodicity sandwiched between two semi-infinite cladding regions of lower effective index [1]. In order to
uniquely identify pathogens critical to medical and homeland defense applications, the PCS was functionalized with a
single stranded probe molecule providing highly specific binding for the target DNA. Integrated microfluidic channels
provide delivery of the pathogen DNA resulting in hybridization and binding in the PCS holes. The binding event
changes the refractive index of the PCS which results in a measurable change in the transmitted power. We will discuss
design parameters and the suite of modeling tools used to optimize the PCS, defect waveguide, and coupling devices.
An overview of the fabrication methods and tools will be provided and we will also report preliminary experimental
results.
Deployable polarimetric imaging systems often use 2×2 arrays of linear polarizers at the pixel level to measure the
polarimetric signature. This architecture is referred to as a micro-grid polarizer array (MPA). MPAs are either bonded to
or fabricated directly upon focal plane arrays. A key challenge to obtaining polarimetric measurements of sub-pixel
targets using MPAs is registering the signals from each of the independent channels. Digital Fusion Solutions, Inc has
developed a micro-optic approach to register the fields of view of 2x2 subarrays of pixels and incorporated the device
into the design of a polarimetric imager. Results of the design will be presented.
The modern threat for electronic support measure (ESM) receivers are radars that use exotic wideband modulation waveforms for achieving higher resolution or reducing the probability of intercept. Existing ESM testbeds can receive both narrowband and wide-bandwidth modulations but can only detect the presence of narrowband signals. A wideband acousto-optic (AO) correlator (AOC) has been jointly developed by the Army Research Laboratory and Dynetics, Inc., under the ARPA TOPS program for insertion into an existing ESM testbed. The AO module is an in-line, time-integrating correlator architecture that offers a small, lightweight solution for detecting and analyzing inherently wide-bandwidth, spread-spectrum signals. The correlator processes 500 MHz of instantaneous bandwidth and offers enhanced detection capability of direct-sequence, phase-modulated chirps, and frequency-hopping signals. The ESM testbed, developed by the Intelligence and Electronic Warfare Directorate of the US Army Communications and Electronics Command, is currently being evaluated for integration into existing and future Army platforms. The AOC complements the existing ESM testbed and offers a wideband detection capability as described in this paper. The AOC insertion with the ESM testbed was demonstrated at the International Low Probability of Intercept Trials in Salisbury, australia. Performance results for the AOC against realistic LPI waveforms from this field test will be presented.
The acousto-optic (AO) module described in this paper is an in-line, time- integrating correlator architecture that detects and analyzes inherently wide bandwidth signals in a small and lightweight package. The correlator processes a 500 MHz instantaneous bandwidth to provide enhanced detection capability for broadband signals. The existing electronic support measures (ESM) testbed processes a wide bandwidth but can only detect the presence of narrowband signals. This paper will describe the AO correlator design and the radio frequency and digital interface required for the insertion into the ESM testbed.
An acousto-optic (AO) correlator is being constructed that offers a small, lightweight solution to detecting and analyzing wide-bandwidth, spread-spectrum signals. The processor is being inserted into an existing electronic support measure (ESM) test-bed under the Defense Advanced Research Projects Agency (DARPA) Transition of Optical Processors into Systems (TOPS) program. The correlator has a processing bandwidth of 500 MHz and will be used to detect direct-sequence, phase-modulated signals, frequency-hopped signals, chirps, and impulses. A description of the processor is provided along with experimental results obtained from an interim developmental breadboard. Subsequent digital processing, which includes nonlinear detection and Fourier transformation, is used to determine center frequencies, bandwidths, and band shape. Theoretical descriptions of the post-processing are provided and simulations results are discussed.
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