Abstract: Techniques are disclosed for improving pump absorption and efficiency for fiber lasers and amplifiers, for instance. In some embodiments, the techniques are implemented by applying a partially reflective coating on a fiber end-face to double-pass any unabsorbed or otherwise excess pump light in the cladding of a fiber. While being reflective to pump wavelengths, the coating can be non-reflective at the lasing wavelength, so as to avoid unwanted feedback into the system. The benefits of this approach include that excess pump power can be effectively utilized to add more power to the laser output. In addition, the double-pass technique allows for the use of a shorter fiber length, which in turn allows for more compact system designs, saves on material costs, and facilitates manufacturability.

Abstract: Techniques are disclosed for improving the quantum efficiency of photocathode devices. The techniques allow for an increase in the optical thickness of the photocathode device, while simultaneously allowing for an increase in the probability of electron escape into the vacuum of the device. The techniques are particularly useful in detector and imaging. In one embodiment, a photocathode device is provided that has an array of corner cubes fabricated in a surface of the photocathode. The corner cube array is made of the same material as the photocathode layer. The device may be, for example, a detector or image intensifier that operates in the UV, visible, and IR light spectrums, and may further include a gain medium, anode, and readout device. Techniques for forming the device are also provided.

Abstract: A MMIC amplifier is directly connected to the balanced feed points at the aperture of an antenna to eliminate the distance between electronics coupled to the antenna and the antenna itself, such that interfaces, components and connection lines which introduce losses and parasitic effects that degrade system performance are eliminated due the direct connection. Expanding the aperture of the antenna to accommodate the direct connection of a MMIC amplifier to balanced feed points of an antenna has been found to have no deleterious effects on antenna performance. Moreover, when coupling the MMIC amplifier to an unbalanced coaxial line, any associated ripple is minimized due to the direct connection.

Abstract: In some embodiments, authentication, confidentiality, and privacy are enhanced for a wireless network of cognitive radios by encryption of network management and control messages as well as data traffic, thereby protecting information pertaining to node identification, node location, node-sensed incumbent transmissions, CRN frequency channel selections, and such like. During initial network registration, a temporary ID can be issued to a node, and then replaced once encrypted communication has been established. This prevents association of initial, clear-text messages with later encrypted transmissions. Elliptic curve cryptography can be used for mutual authentication between subscribers and the base station. ECC-based implicit digital certificates can be embedded in co-existence beacons used by CRN nodes to coordinate use of frequency channels, thereby preventing denial of service attacks due to transmitting of falsified beacons.

Abstract: A low cost, lightweight frangible wing slot seal can be applied to a guidance wing slot of a folding fin aerial rocket or missile, providing a barrier against exposure of internal missile components to external contaminants, while allowing unhindered deployment of missile guidance wings simply by bursting through the seals. The simple design is nearly foolproof, and has no impact the likelihood of weapon failure. The seal is a flexible sheet which is sufficiently thin so as not to exceed the required volume envelope of the missile. The sheet includes a burst seam, which is breached when impacted by the leading edge of a deploying wing. No additional wing deployment force is required, and after deployment the seal has minimal impact on the aerodynamic performance of the wing.

Abstract: Various embodiments of the present invention relate to weighted waveforms for improved jam code effectiveness. In various examples, weighted waveforms for improved jam code effectiveness may be implemented in the context of systems, methods, computer program products and/or algorithms.

Abstract: Techniques are disclosed that provide a high-speed synchronized interface for command and control between the sensor and the laser of countermeasure systems. The techniques may be implemented, for example, in a countermeasure system configured for operation with a laser and sensor, wherein the system includes an interface with laser and sensor command control words synchronized with a master clock having an embedded System Heart Beat defining a Master Frame period, a command and control protocol for the laser and the sensor within the Master Frame period; and a T0 sensor to measure the time a laser pulse leaves the system, wherein the sensor uses the measured time as reference to set frame start and timing measurements. The system may support both active ranging and passive tracking (e.g., Master Frame period may include both passive and active sub-frames). The active ranging may include both coarse and fine resolution ranging.

Abstract: A method for fabricating butt-coupled electro-absorptive modulators is disclosed. A butt-coupled electro-absorptive modulator with minimal dislocations in the electro-absorptive material is produced by adding a dielectric spacer for lining the coupling region before epitaxially growing the SiGe or other electro-absorptive material. It has been determined that during the SiGe growth, the current process has exposed single crystal silicon at the bottom of the hole and exposed amorphous silicon on the sides. SiGe growth on the amorphous silicon is expected to have more dislocations than single crystal silicon. There should also be dislocations or fissures where the SiGe growth from the each nucleation source finally join. Thus, a dielectric sidewall can protect an exposed waveguide face from any etching from an aggressive surface preparation prior to epi growth.

Abstract: Techniques are disclosed for computing distance-to-fault (DTF) in communication systems. The techniques can be embodied, for instance, in a DTF system that provides a multi-port probing device and DTF functionality, including computing distances to faults and the fault magnitudes. In addition, the DTF system is further configured with the ability to accurately measure complex reflection coefficient of the UUT, and/or return loss of the UUT. The complex reflection coefficient and/or return loss of the UUT can be computed as a function of known scattering parameters of a multi-port measurement circuit included in the probe of the DTF system.

Abstract: A compact, lens suitable for airborne photography and mapping has distortion less than 0.6% and is athermal from ?15° C. to +40° C. The lens is near-telecentric to less than 11°, apochromatic over the wavelength range 450 nm-650 nm, and has a full field of view of 60° (high quality field over 53°). The lens can be secondary color corrected. In embodiments, the focal length is 101 mm and the back working distance is more than 10 mm. Embodiments have a focal plane diameter of 104 mm and are compatible for use with a CMOS 1.8 gigapixel multiple FPA. In embodiments, the lens comprises three groups of optical elements, with an aperture located within the second optical group. In some embodiments the first group includes two elements, the second group includes six or seven elements, and the third group include three elements. In embodiments the lens (without window) is less than 180 mm long.

Abstract: A system and method for mitigating Analog to Digital (A/D) clipping is disclosed. The mean and variance of analog input data are tracked and the bits of A/D are dynamically reassigned to keep the input signal within their range. The quantization levels of A/D are dynamically re-mapped to avoid changes in sensitivity of sensor system. The method is based on random walk statistic and keeps the sensitivity of the sensor system constant. Also the system and method provides a way to mitigate A/D clipping that avoids changing the sensitivity by dynamically re-mapping the quantization levels of the A/D, keeping the sensitivity of the system constant.

Abstract: A method for fabricating an image panel for a hyperspectral camera that is configured to scan a scene and obtain spectral image data over as defined range of wavelengths. At least one companion sensor is first fabricated on a planar imaging surface of a silicon die. At least as region of the silicon die is then back thinned to a diffraction thickness that is suitable for a diffraction slit. A diffraction slit is then formed in the thinned region so that the diffraction slit penetrates the silicon die in the thinned region, and the diffraction slit is co-planar with the imaging surface of the silicon die.

Abstract: A method and apparatus for applying a mid-IR graded microstructure to the end of an As2S3 optical fiber are presented herein. The method and apparatus transfer a microstructure from a negative imprint on a nickel shim to an As2S3 fiber tip with minimal shape distortion and minimal damage-threshold impact resulting in large gains in anti-reflective properties.

Abstract: A system for enabling interoperability among various kinds of communications equipment and information transmission formats on the battlefield or during tactical missions. The system includes a multi-message translator (MMT) for translating a source text message having a first set of word fields defined according to a source message format, into a sink message having a second set of word fields defined according to a sink message format. The system also includes a voice bridging gateway (VBG) for bridging multiple voice communication networks having associated transmission protocols that are incompatible with one another. Dismounted soldiers obtain location based services including geo-referenced maps, and tactical communications including voice and text messaging, using smart phones or other lightweight COTS client devices that link through a personal networking node (PNN) server to one or both of the MMT and the VBG.

Abstract: An apparatus and method for reducing nonlinearity artifacts in an IR imaging system applies a non-linear correcting function to signals received from a microbolometer. The non-linear correcting function can be a second-order polynomial, a third-order polynomial, some other formula, or a table from which corrections can be interpolated. In embodiments, the correcting function is automatically adjusted according to an ambient temperature measurement, to which a non-linear correction can be applied, either in a separate step or as an adjustment to the correcting function applied to the microbolometer signals.

Abstract: A system and method for allowing individual register access during system integration and test is disclosed. A Chip select is routed between an OMAP processor and a waveform FPGA and configured to allow individual register access during system integration and test. Logic is then added to the FPGA to support the single access to the FPGA's peripherals. This allows the user connected to the debug port to be able to send and receive individual commands to and from the waveform FPGA's peripherals. A Graphical User Interface (GUI) maybe developed to provide a graphical interface or scripts may be used to assemble multiple commands thereby increasing flexibility to configure the peripherals during integration and troubleshooting.

Abstract: Embodiments of a method and apparatus for controlling the mechanical stabilization of an optical fiber are disclosed. The method may consist of placing an inflatable bladder between an optical fiber and a protective jacket. The bladder may be inflated with air, inert gas, or liquid to a desired pressure. The bladder may be sectioned to extend along part of or the entire length of the fiber. The bladder may isolate the optical fiber in a periodic fashion. The temperature of the material inside the bladder may vary axially along the optical fiber. Embodiments of the invention can stabilize the optical fiber by providing mechanical isolation from vibration and other perturbations. Embodiments of the invention can also alter Stimulated Brillouin Scattering (“SBS”) and Stimulated Raman Scattering (“SRS”) thresholds using either thermal or vibrational perturbations.

Abstract: Analytes are rapidly desorbed from a carbonaceous sorbent powder with improved quantitation and reduced analyte re-adsorption, thermal degradation, and rearrangement. The sample is distributed in a thin layer onto a desorption surface within a chamber. The layer can be a monolayer. Heating light irradiates the sample through a window, directly and rapidly heating the sample while the desorbed analytes diffuse into a vacuum or are removed by a carrier gas. Finally, the sorbent is flushed from the chamber by a transport gas. The desorption surface can be an inner surface of the window, or a surface of a porous frit that divides the chamber into two sections. The frit can be stainless steel or glass. The carrier gas can be helium, argon, or carbon dioxide. The light source can be a tungsten halogen lamp. A heater can control the chamber temperature according to a heating profile.

Abstract: In the method for processing a signal light from free-space by amplifying said signal for free-space optical communications, wherein the improvement includes the steps of (a) pre-amplifying said signal light with low noise; and (b) coupling said signal light into a multimode filter which reduces coupling losses compared to single mode filters.

Abstract: A communications radio or transceiver having an extended upper operating frequency limit of at least 6 GHz. The radio includes a first IF conversion stage for receiving and downconverting a RF input signal to a first IF signal, and a second IF conversion stage for downconverting the first IF signal to a second IF signal. The first and the second conversion stages each have adjustable first and second attenuators, a serial peripheral interface (SPI) for controlling the attenuators in response to command words, a mixer coupled to an output of the second attenuator, and a buffer for applying a local oscillator (LO) signal to an input of the mixer. Each conversion stage is in the form of an integrated circuit chip. Component devices of each chip and electrical connections between the components, are dimensioned so that the chip has a 6 GHz upper frequency limit.