This technology relates to a plasma diagnostic method by directing THz radiation into plasma and detecting an emission due to the interaction of the THz radiation with the plasma to characterize the plasma. Terahertz (THz) waves occupy a segment of the electromagnetic spectrum between the infrared and microwave bands. As such, they can be used for imaging and sensing in ways not possible with conventional technologies such as X-ray and microwave.

This technology relates to detecting terahertz radiation using an optical beam in a volume of gas. Ionizing a portion of the volume of gas with the optical beam produces a plasma and fluorescence is produced from an interaction of a radiation wave with the plasma. Information contained in the characteristics of the detected fluorescence can be used to characterize the radiation wave. Terahertz (THz) waves occupy a segment of the electromagnetic spectrum between the infrared and microwave bands.

This technology relates to high electron mobility transistors (HEMT). In conventional off-type HEMTs, a large amount of gate threshold voltage variation is often found. Transistors according to this technology include a p-type region, a barrier region, an insulation film, a gate electrode, and a channel region. The channel region is connected to an upper surface of the p-type region. The channel region is n-type or i-type and provided with a first channel region and a second channel region. The barrier region is forming a hetero-junction with an upper surface of the first channel region.

This technology provides an improved MOSFET structure for power switching applications. An n- GaN reduced surface field (RESURF) region is created using epitaxial growth and selective etching of an n- drift layer. This is followed by ion implantation to achieve n GaN contact regions for the source and drain. This avoids the difficulties in controlling doping levels, leakage current, and electron mobility when using ion implantation alone to achieve the two different doping zones.

This technology couples the physical layer characteristics of wireless networks with key generation algorithms. It is based on the wireless communication phenomenon known as the principle of reciprocity which states that in the absence of interference both transmitter and receiver experience the same signal envelope. Signal envelope information can provide to the two transceivers two correlated random sources that provide sufficient amounts of entropy which can be used to extract a cryptographic key.

Many THz systems have very limited portability and mobility due to their large size and sensitivity to vibrations, pressures, and torque loadings. Further, much of the demand for THz technology comes from research, industrial, and military applications where the operator is not expected to have experience in advanced optical systems. For most field applications, especially for defense applications, a mobile, robust, turnkey, miniature, or handheld THz time-domain spectrometer is essential.

Using air as an emitting medium to generate terahertz wave has attracted attention because of its potential applications for remote distance THz wave sensing and imaging. Yet, the cutting edge energy conversion efficiency of THz wave generation with optical method is extremely low. Researchers at Rensselaer have developed a method for generating amplified terahertz radiation that includes inducing a first volume of a gas to produce a seed plasma and emit pulsed seed terahertz radiation by focusing an optical seed beam in the first volume.

Using air as an emitting medium to generate terahertz wave has attracted attention because of its potential applications for remote distance THz wave sensing and imaging. Yet, the cutting edge energy conversion efficiency of THz wave generation with optical method is extremely low. Researchers at Rensselaer have developed a method for generating amplified terahertz radiation that includes inducing a first volume of a gas to produce a seed plasma and emit pulsed seed terahertz radiation by focusing an optical seed beam in the first volume.

Terahertz wave imaging has been used in various applications, such as security sensing and quality control inspection, for example. Terahertz wave two-dimensional (2D) imaging technology has been demonstrated as it dramatically reduces the time required for image acquisition. It can also support real-time terahertz wave imaging.

Since terahertz (THz) wave spectroscopy has been utilized to detect a number of chemical and explosive materials and related compounds by providing their spectral signatures in the THz frequency range, there is an interest in THz wve spectroscopy as a technique to sense improvised explosive devices. However, due to the severe water vapor attenuation of THz waves in the atmosphere, the reliable sensing range of THz wave spectroscopy has been limited to relatively short distances.