Abstract: Lidar uses light to sense the range to an object. It can be used as a sensor, e.g., for autonomous vehicle navigation, or to generate detailed maps of terrain. A lidar can also sense target speed, optical reflectivity, and spectroscopic signature. As lidars become more widespread, one lidar could interfere with another nearby lidar. Incoherent (time of flight (TOF)) lidars can also be spoofed or hacked. And both coherent and incoherent lidars can be jammed. Modulating the lidar source makes the lidar more resistant to interference, jamming and hacking. In a TOF lidar, each transmitted pulse is modulated in a prearranged or predetermined fashion. A processor in the receiver distinguishes true returns from actual returns based on the modulation or encoding of the transmitted pulses. If the modulation is present, the return signal considered genuine. If the modulation is not present, it is deemed fake.

Abstract: Lidar uses light to sense the range to an object. It can be used as a sensor, e.g., for autonomous vehicle navigation, or to generate detailed maps of terrain. A lidar can also sense target speed, optical reflectivity, and spectroscopic signature. As lidars become more widespread, one lidar could interfere with another nearby lidar. Incoherent (time of flight (TOF)) lidars can also be spoofed or hacked. And both coherent and incoherent lidars can be jammed. Modulating the lidar source makes the lidar more resistant to interference, jamming and hacking. In a TOF lidar, each transmitted pulse is modulated in a prearranged or predetermined fashion. A processor in the receiver distinguishes true returns from actual returns based on the modulation or encoding of the transmitted pulses. If the modulation is present, the return signal considered genuine. If the modulation is not present, it is deemed fake.

Abstract: Disclosed herein are a system and corresponding method for sensing terahertz radiation. The system collects terahertz radiation scattered from a target and upconverts the collected radiation to optical frequencies. A frequency-domain spectrometer senses spectral components of the upconverted signal in parallel to produce a spectroscopic measurement of the entire band of interest in a single shot. Because the sensing system can do single-shot measurements, it can sense moving targets, unlike sensing systems that use serial detection, which can only be used to sense stationary objects. As a result, the sensing systems and methods disclosed herein may be used for real-time imaging, including detection of concealed weapons, medical imaging, and hyperspectral imaging.

Abstract: Disclosed herein are a system and corresponding method for sensing terahertz radiation. The system collects terahertz radiation scattered from a target and upconverts the collected radiation to optical frequencies. A frequency-domain spectrometer senses spectral components of the upconverted signal in parallel to produce a spectroscopic measurement of the entire band of interest in a single shot. Because the sensing system can do single-shot measurements, it can sense moving targets, unlike sensing systems that use serial detection, which can only be used to sense stationary objects. As a result, the sensing systems and methods disclosed herein may be used for real-time imaging, including detection of concealed weapons, medical imaging, and hyperspectral imaging.

Abstract: Disclosed herein are a system and corresponding method for sensing terahertz radiation. The system collects terahertz radiation scattered from a target and upconverts the collected radiation to optical frequencies. A frequency-domain spectrometer senses spectral components of the upconverted signal in parallel to produce a spectroscopic measurement of the entire band of interest in a single shot. Because the sensing system can do single-shot measurements, it can sense moving targets, unlike sensing systems that use serial detection, which can only be used to sense stationary objects. As a result, the sensing systems and methods disclosed herein may be used for real-time imaging, including detection of concealed weapons, medical imaging, and hyperspectral imaging.

Abstract: A method for cross connecting optical signals includes using a common beam steerer to direct a set of optical signals from a set of input ports to a set of output ports. The method further includes adjusting a curvature of the common beam steerer so that paths of the optical signals have substantially the same effective path length.

Abstract: Disclosed herein are a system and corresponding method for sensing terahertz radiation. The system collects terahertz radiation scattered from a target and upconverts the collected radiation to optical frequencies. A frequency-domain spectrometer senses spectral components of the upconverted signal in parallel to produce a spectroscopic measurement of the entire band of interest in a single shot. Because the sensing system can do single-shot measurements, it can sense moving targets, unlike sensing systems that use serial detection, which can only be used to sense stationary objects. As a result, the sensing systems and methods disclosed herein may be used for real-time imaging, including detection of concealed weapons, medical imaging, and hyperspectral imaging.

Abstract: A method for cross connecting optical signals includes using a common beam steerer to direct a set of optical signals from a set of input ports to a set of output ports. The method further includes adjusting a curvature of the common beam steerer so that paths of the optical signals have substantially the same effective path length.

Abstract: A method for cross connecting optical signals includes using a common beam steerer to direct a set of optical signals from a set of input ports to a set of output ports. The method further includes adjusting a curvature of the common beam steerer so that paths of the optical signals have substantially the same effective path length.

Abstract: Described are a sensor and a method for measuring a vibration of a surface obscured from view. The sensor includes a narrowband source of a terahertz beam, a beamsplitter, a beam combiner and a terahertz detector. The beamsplitter splits the terahertz beam into a sample beam for irradiating the surface and a reference beam. The beam combiner combines the sample beam scattered from the surface and the reference beam. The terahertz detector generates an electrical signal based on a modulation of the power of the combined beams due to the vibrating surface. The electrical signal indicates a characteristic of the surface vibration. Homodyne or heterodyne detection can be utilized. Advantageously, the sensor can see surfaces that are covered, concealed or otherwise obscured behind optically opaque materials, including plastic, cloth, foam, paper and other materials. Thus the sensor has a wide variety of applications where conventional vibrometers are not practical.

Abstract: A method for cross connecting optical signals includes using a common beam steerer to direct a set of optical signals from a set of input ports to a set of output ports. The method further includes adjusting a curvature of the common beam steerer so that paths of the optical signals have substantially the same effective path length.

Abstract: A method for cross connecting optical signals includes using a common beam steerer to direct a set of optical signals from a set of input ports to a set of output ports. The method further includes adjusting a curvature of the common beam steerer so that paths of the optical signals have substantially the same effective path length.

Abstract: Described are a sensor and a method for measuring a vibration of a surface obscured from view. The sensor includes a narrowband source of a terahertz beam, a beamsplitter, a beam combiner and a terahertz detector. The beamsplitter splits the terahertz beam into a sample beam for irradiating the surface and a reference beam. The beam combiner combines the sample beam scattered from the surface and the reference beam. The terahertz detector generates an electrical signal based on a modulation of the power of the combined beams due to the vibrating surface. The electrical signal indicates a characteristic of the surface vibration. Homodyne or heterodyne detection can be utilized. Advantageously, the sensor can see surfaces that are covered, concealed or otherwise obscured behind optically opaque materials, including plastic, cloth, foam, paper and other materials. Thus the sensor has a wide variety of applications where conventional vibrometers are not practical.

Abstract: The present invention relates to an optical signal shaping device such as an optical filter having a profile such that transmission of light through the device varies as a function of frequency over a selected bandwidth. The optical signal shaping device of the present invention includes a frequency dependent disperser that disperses the input optical signal to form a dispersed signal having a plurality of frequencies, a frequency selective modulator that modulates at least one of the plurality of frequencies and a frequency dependent combiner that combines the frequencies to form a modulated output signal.

Abstract: Changing the phrases when mixing of optical modes gives rise to intensity effects. This occurs in multi-mode interferometer (MMI) or arrayed waveguide gratings (AWG). Here we use an electro-arefractive modulator, with a quadratic electro-optic effect that has an optical transfer function (Or power vs voltage (L-V) curve) given by is Pout=Pin (1+? cos ?)/2 where asymmetry factor ? measures the extinction ratio and the phase difference ? between arms is ? ? ? V 2 V ? 2 ? ? ? V 2 V ? 2 . In turn, the voltage V is expressed as a sum of the DC bias and RF drive V=VDC+VRF.

Abstract: A closed-loop, dome thermal control apparatus containing a high-volume fan, a heat exchange chamber, and an enclosure that encloses the fan and the heat exchange chamber. The fan blows air over a dome of a semiconductor wafer processing system and through the heat exchange chamber to uniformly control the temperature of a dome of a plasma chamber to prevent particle contamination of the wafer. The enclosure recirculates the temperature controlled air to the fan to form a closed-loop apparatus.

Abstract: Temperature control of a process chamber 25 is achieved by directing a flow of gas at an external surface 100 of the chamber 25. In one aspect, gas directed at the chamber 25 passes through a gas flow amplifier 115 that increases the gas flow. Gas for the temperature control can be drawn in from the ambient air and, after passing over the process chamber 25, the gas can flow out through an outlet 150. Data is presented demonstrating superior temperature control performance over a conventional system.