Abstract: A photonic feedforward analog-to-digital converter (ADC) is provided. According to one aspect of the invention, the signal to be digitized is applied to only one electro-optic modulator. High speed is achieved by taking advantage of the fundamental property of a Pockels Cell to control wave polarization using the electro-optic effect. In a further aspect, once a bit is determined, its state is fed forward to the next least significant bit to aid in determination of the next lower bit. This nonlinear feedforward aspect of the ADC provides simplicity of its architecture.

Abstract: A photonic feedforward analog-to-digital converter (ADC) is provided. According to one aspect of the invention, the signal to be digitized is applied to only one electro-optic modulator. High speed is achieved by taking advantage of the fundamental property of a Pockels Cell to control wave polarization using the electro-optic effect. In a further aspect, once a bit is determined, its state is fed forward to the next least significant bit to aid in determination of the next lower bit. This nonlinear feedforward aspect of the ADC provides simplicity of its architecture.

Abstract: A thermal acoustic imaging (TAI) system includes a source of continuous amplitude-modulated RF or microwaves for irradiating a tissue region to be imaged, wherein a modulation frequency of the RF of microwaves resonantly excite the tissue region to emit thermal acoustic signals in response. The source preferably provides a substantially uniform power distribution in the region to be imaged. An acoustic transducer receives the thermal acoustic signals and generates an electrical signal in response. Matched filtering matched to a frequency of the amplitude-modulated RF or microwaves followed by delay-and sum or adaptive methods are preferably used to generate images from the electrical signals. The acoustic transducer is preferably a micro-electromechanical system (MEMS) transducer.

Abstract: A photonic, wide-band analog to digital converter and method for converting an analog electrical signal to a digital electrical signal by electrical signal processing wherein the analog electrical signal is first converted to an optical signal having a wavelength which is a function of the amplitude of said analog electrical signal. The optical signal is then filtered in a plurality of optical filter channels to create N optical bit signals forming an N bit binary word indicating the wavelength of said optical signal. These optical bit signals are then each converted to an electrical bit signal to form an electrical binary word.

Abstract: A one-laser technique for optical time-delay beamsteering of a microwave phased-array antenna in transmit-and- receive modes. Arrays of reflective, fiber Bragg gratings are employed and a modulated, wavelength-tuned laser excites prism-shaped arrays of chirped or single-frequency gratings deployed inside a set of N parallel fibers. The fiber gratings can be replaced by waveguided gratings within a semiconductor chip for operation at high microwave frequencies.

Abstract: A variable time delay system for broadband phased array receive and other transversal filtering applications is disclosed and employs a segmented mirror device (SMD) and a linear fiber array to realize a quantized variable delay line. The use of the SMD allows for extremely high packing density without the large losses usually associated with switched fiber schemes.

Abstract: By applying a spatial frequency dependent phase compensation in an optical heterodyning system, a variable rf delay line can be synthesized. The system is able to generate continuously variable phased microwave signals over a prescribed frequency band. A primary application of these variable delay lines is in the area of phased array antenna systems. Because the phototonic delay line synthesizes true time delay, it can be used as part of wide bandwidth system to achieve 100% fractional bandwidth without beam squint. The system lends itself to an optically integrated implementation using a 2-D deformable mirror device to achieve very high packing density which is very useful for an adaptive transversal filter.