Abstract: A terahertz scanner for detecting irregularities, such as chemical or structural variations, in a sample and methods of use thereof are described. The described terahertz scanner and algorithms allow for direct, high-sensitivity, high-throughput, and non-invasive detection of irregularities that range from chemical contaminant to material defects in a variety of substrates and settings.

Abstract: Systems and methods for performing wavelength conversion via plasmon-coupled surface states are described that can be used for optical wavelength conversion to different parts of the electromagnetic spectrum ranging from microwave to infrared regimes in both pulsed and continuous wave operation.

Abstract: A terahertz scanner for detecting irregularities, such as chemical or structural variations, in a sample and methods of use thereof are described. The described terahertz scanner and algorithms allow for direct, high-sensitivity, high-throughput, and non-invasive detection of irregularities that range from chemical contaminant to material defects in a variety of substrates and settings.

Abstract: Methods and systems for determining water status in plant tissue are provided. A number of systems are capable of using terahertz signals to generate signals measuring total water content in plant tissue, including plant leaves. Using these signals, methods are capable of determining water status variables, including water mass per leaf area, relative water content, and leaf water potential, which can aid in agricultural, ecological, and environmental health, such as dehydration and droughst stress of plants.

Abstract: Nanocomposites in accordance with many embodiments of the invention can be capable of converting electromagnetic radiation to an electric signal, such as signals in the form of current or voltage. In some embodiments, metallic nanostructures are integrated with graphene material to form a metallo-graphene nanocomposite. Graphene is a material that has been explored for broadband and ultrafast photodetection applications because of its distinct optical and electronic characteristics. However, the low optical absorption and the short carrier lifetime of graphene can limit its use in many applications. Nanocomposites in accordance with various embodiments of the invention integrates metallic nanostructures, such as (but not limited to) plasmonic nanoantennas and metallic nanoparticles, with a graphene-based material to form metallo-graphene nanostructures that can offer high responsivity, ultrafast temporal responses, and broadband operation in a variety of optoelectronic applications.

Abstract: Many embodiments provide a high frequency near-field probe based on a tapered waveguide combined with at least one optically-pumped high frequency radiation source and at least one optically-probed high frequency radiation detector.

Abstract: A photoconductive device that includes a semiconductor substrate, an antenna assembly, and a photoconductive assembly with one or more plasmonic contact electrodes. The photoconductive assembly can be provided with plasmonic contact electrodes that are arranged on the semiconductor substrate in a manner that improves the quantum efficiency of the photoconductive device by plasmonically enhancing the pump absorption into the photo-absorbing regions of semiconductor substrate. In one exemplary embodiment, the photoconductive device is arranged as a photoconductive source and is pumped at telecom pump wavelengths (e.g., 1.0-1.6 ?m) and produces milliwatt-range power levels in the terahertz (THz) frequency range.

Abstract: A photoconductive device that includes a semiconductor substrate, an antenna assembly, and a photoconductive assembly with one or more plasmonic contact electrodes. The photoconductive assembly can be provided with plasmonic contact electrodes that are arranged on the semiconductor substrate in a manner that improves the quantum efficiency of the photoconductive device by plasmonically enhancing the pump absorption into the photo-absorbing regions of semiconductor substrate. In one exemplary embodiment, the photoconductive device is arranged as a photoconductive source and is pumped at telecom pump wavelengths (e.g., 1.0-1.6 ?m) and produces milliwatt-range power levels in the terahertz (THz) frequency range.

Abstract: A system for detecting high-frequency radiation that offers near-quantum-limited sensitivity, broad spectral bandwidth, and high spectral resolution while operating at room temperature. The system can include an antenna assembly configured to receive at least a high-frequency radiation and a substrate comprising a semiconductor material with a contact-semiconductor interface connected to the antenna assembly. The system also includes an optical pump configured to produce an optical beam that has a high-frequency beat frequency, the optical beam contacting the contact-semiconductor interface to create an intermediate frequency signal by combining the optical beam with the high-frequency radiation. The system further includes a detector configured to detect the intermediate frequency and generate at least one report indicating the received, high-frequency radiation.

Abstract: Terahertz imaging systems for endoscopy are provided. Terahertz imaging systems can be utilized in scanning tissue. Terahertz imaging systems in accordance with embodiments of the invention can include terahertz sources, terahertz detectors, and/or rotating elements. The terahertz sources can generate terahertz radiation and have plasmonic contact electrodes that can be illuminated by optical pump beams. The terahertz detectors can receive terahertz field data. The terahertz source and detector can be arranged in an array. The rotating elements can be mirror mounted at a particular angle on a micromotor. The terahertz source, rotating element, and terahertz detector can be arranged in an catheter.

Abstract: A photoconductive device that includes a semiconductor substrate, an antenna assembly, and a photoconductive assembly with one or more plasmonic contact electrodes. The photoconductive assembly can be provided with plasmonic contact electrodes that are arranged on the semiconductor substrate in a manner that improves the quantum efficiency of the photoconductive device by plasmonically enhancing the pump absorption into the photo-absorbing regions of semiconductor substrate. In one exemplary embodiment, the photoconductive device is arranged as a photoconductive source and is pumped at telecom pump wavelengths (e.g., 1.0-1.6 ?m) and produces milliwatt-range power levels in the terahertz (THz) frequency range.

Abstract: Nanocomposites in accordance with many embodiments of the invention can be capable of converting electromagnetic radiation to an electric signal, such as signals in the form of current or voltage. In some embodiments, metallic nanostructures are integrated with graphene material to form a metallo-graphene nanocomposite. Graphene is a material that has been explored for broadband and ultrafast photodetection applications because of its distinct optical and electronic characteristics. However, the low optical absorption and the short carrier lifetime of graphene can limit its use in many applications. Nanocomposites in accordance with various embodiments of the invention integrates metallic nanostructures, such as (but not limited to) plasmonic nanoantennas and metallic nanoparticles, with a graphene-based material to form metallo-graphene nanostructures that can offer high responsivity, ultrafast temporal responses, and broadband operation in a variety of optoelectronic applications.

Abstract: Many embodiments provide a high frequency near-field probe based on a tapered waveguide combined with at least one optically-pumped high frequency radiation source and at least one optically-probed high frequency radiation detector.

Abstract: Terahertz imaging systems for endoscopy are provided. Terahertz imaging systems can be utilized in scanning tissue. Terahertz imaging systems in accordance with embodiments of the invention can include terahertz sources, terahertz detectors, and/or rotating elements. The terahertz sources can generate terahertz radiation and have plasmonic contact electrodes that can be illuminated by optical pump beams. The terahertz detectors can receive terahertz field data. The terahertz source and detector can be arranged in an array. The rotating elements can be mirror mounted at a particular angle on a micromotor. The terahertz source, rotating element, and terahertz detector can be arranged in an catheter.

Abstract: Systems and methods for plasmonics enhanced photomixing for generating continuous-wave (CW) frequency-tunable terahertz radiation in accordance with embodiments of the invention are disclosed. A photomixing system configured to generate continuous-wave terahertz frequency signals can include an optical pump configured to generate at least two beams, where the at least two beams are utilized to create a frequency-offset and operate below a 50% duty cycle, where the duty cycle includes an operation cycle and a sleep cycle. The photomixing system can also include a photomixer that includes a radiating element configured to receive the frequency-offset and to generate a terahertz radiation utilizing the received frequency-offset and the radiating element, where the radiating element includes at least one plasmonic contact electrode.

Abstract: A photoconductive device that includes a semiconductor substrate, an antenna assembly, and a photoconductive assembly with one or more plasmonic contact electrodes. The photoconductive assembly can be provided with plasmonic contact electrodes that are arranged on the semiconductor substrate in a manner that improves the quantum efficiency of the photoconductive device by plasmonically enhancing the pump absorption into the photo-absorbing regions of semiconductor substrate. In one exemplary embodiment, the photoconductive device is arranged as a photoconductive source and is pumped at telecom pump wavelengths (e.g., 1.0-1.6 ?m) and produces milliwatt-range power levels in the terahertz (THz) frequency range.

Abstract: A reconfigurable device for terahertz (THz) or infrared (IR) ranges that includes a base substrate, a lower array attached to the base substrate, and an upper array attached to the base substrate and at least partially suspended over the lower array. Activation of the reconfigurable device causes the upper array to mechanically flex towards the lower array so that electrical contact is made therebetween. Methods of fabricating and operating the reconfigurable device are also provided.

Abstract: A photoconductive device that includes a semiconductor substrate, an antenna assembly, and a photoconductive assembly with one or more plasmonic contact electrodes. The photoconductive assembly can be provided with plasmonic contact electrodes that are arranged on the semiconductor substrate in a manner that improves the quantum efficiency of the photoconductive device by plasmonically enhancing the pump absorption into the photo-absorbing regions of semiconductor substrate. In one exemplary embodiment, the photoconductive device is arranged as a photoconductive source and is pumped at telecom pump wavelengths (e.g., 1.0-1.6 ?m) and produces milliwatt-range power levels in the terahertz (THz) frequency range.

Abstract: Systems and methods for plasmonics enhanced photomixing for generating continuous-wave (CW) frequency-tunable terahertz radiation in accordance with embodiments of the invention are disclosed. A photomixing system configured to generate continuous-wave terahertz frequency signals can include an optical pump configured to generate at least two beams, where the at least two beams are utilized to create a frequency-offset and operate below a 50% duty cycle, where the duty cycle includes an operation cycle and a sleep cycle. The photomixing system can also include a photomixer that includes a radiating element configured to receive the frequency-offset and to generate a terahertz radiation utilizing the received frequency-offset and the radiating element, where the radiating element includes at least one plasmonic contact electrode.

Abstract: A reconfigurable device for terahertz (THz) or infrared (IR) ranges that includes a base substrate, a lower array attached to the base substrate, and an upper array attached to the base substrate and at least partially suspended over the lower array. Activation of the reconfigurable device causes the upper array to mechanically flex towards the lower array so that electrical contact is made therebetween. Methods of fabricating and operating the reconfigurable device are also provided.