William Marsh Rice University

Brown University

Lucent Technologies Inc.

Osaka University

Wm. Marshurice University

Daniel M Mittleman

Masaya Nagai

Rajind Mendis

Martin C Nuss

Edward Knightly

Matthew David Escarra

Kanglin Wang

Ciyuan Qiu

Jason A Deibel

Jon L Johnson

Quinfan Xu

Rune Hylsberg Jacobsen

Jie Shu

An isolator based on a waveguide-based artificial dielectric medium is scalable to a range of desired terahertz frequencies, has non-reciprocal transmission and provides low insertion loss and high isolation at various tunable terahertz frequencies, far exceeding the performance of other terahertz isolators, and rivaling that of commercial optical isolators based on the Faraday effect. Because terahertz artificial dielectrics are low loss, inexpensive, and easy to fabricate, this approach offers a promising new route for polarization control of free-space terahertz beams in various instrumentation applications. Artificial dielectrics are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. A simple and effective strategy implements a polarizing-beam-splitter and a quarter wave plate to form a highly effective isolator. Performance of the device is believed to exceed that of any other experimentally demonstrated method for isolation of back-reflections for terahertz beams.

Artificial dielectric isolator for THz radiation

A multi-frequency wireless access device including a first waveguide having a pair of parallel metal plates with open sides and a slot in one of the metal plates, the slot permitting radiation to leak out, the leaked radiation illuminating a range of angles depending on frequency.

Location information from a receiver in a wireless network

An isolator based on a waveguide-based artificial dielectric medium is scalable to a range of desired terahertz frequencies, has non-reciprocal transmission and provides low insertion loss and high isolation at various tunable terahertz frequencies, far exceeding the performance of other terahertz isolators, and rivaling that of commercial optical isolators based on the Faraday effect. This approach offers a promising new route for polarization control of free-space terahertz beams in various instrumentation applications. Artificial dielectrics are man-made media that mimic properties of naturally occurring dielectric media, or even manifest properties that cannot generally occur in nature. A simple and effective strategy implements a polarizing-beam-splitter and a quarter wave plate to form a highly effective isolator. Performance of the device is believed to exceed that of any other experimentally demonstrated method for isolation of back-reflections for terahertz beams.

A polarizing beam splitter includes thin electrically conductive metal sheets each having an edge and a thickness substantially less than the wavelength &#x3bb; of a terahertz signal. The sheets are arranged in a stack or array to define wave propagation passages for energy of a terahertz beam directed at a face formed by edges of the sheets, and constitutes an artificial dielectric which operates below cutoff to allow selective transmission through the passages and/or reflection from said face, separating polarization states of the beam with defined power splitting. The artificial dielectric beam splitter can be configured to operate over a broad terahertz band. The sheets are flat, without micropatterned surface features, are robust and simple to manufacture, and form a broad band polarizing beam slitter for terahertz radiation. Complete separation of the transmitted and reflected beam is achieved below cutoff by rotating the polarization of the input beam.

Polarizing beam splitter for THz radiation

A system for coupling teraherz (THz) radiation to a coaxial waveguide comprises an antenna that generates THz radiation having a mode that matches the mode of the waveguide. The antenna may comprise a pair of concentric electrodes, at least one of which may be affixed to or formed by one end of the waveguide. The radiation may have wavelengths between approximately 30 &#x3bc;m and 3 mm. The waveguide may comprise an inner core and an outer wall defining an annular region. A terahertz sensor system may comprise a terahertz antenna comprising first and second concentric electrodes, means for generating a field across the trodes and means for triggering the emission of terahertz radiation, a first waveguide having first and second ends, said first end being coupled to said antenna so as to receive at least a portion of said terahertz radiation, and a sensor for detecting said terahertz radiation.

Method for coupling terahertz pulses into a coaxial waveguide

A device for modulating terahertz waves includes a metal layer (703) including a continuous metal portion (705) and island metal portions (707). The metal portions (705, 707) are separated by apertures (709). The device further includes a semiconductor layer (715) affixed to a bottom surface of the metal layer (703). The semiconductor layer (715) includes carrier regions (717) located below the apertures (709). The transmission of terahertz waves through the apertures (709) is modulated by changing a voltage applied across the aperture via voltage source (715). By injecting free carriers into carrier regions (717) due to a change of the voltage an extraordinary terahertz transmission effect of the metal layer (703) can be switched off. A small increase in the free-carrier absorption is significantly enhanced by the Fabry-Perot resonance, resulting in a substantial decrease in transmission. The disclosed ring aperture terahertz modulator allows for electrical control of the carrier density only in the area underneath the aperture. This design minimizes the power consumption and maximizes the operation speed.

Device and method for modulating transmission of terahertz waves

A method comprising polarizing and coupling an electromagnetic beam to a first-order transverse electric (TE) mode with respect to a parallel plate waveguide (PPWG) integrated resonator comprising two plates and a cavity, sending the electromagnetic beam into the PPWG integrated resonator to excite the cavity by the TEmode and cause a resonance response, and obtaining wave amplitude data that comprises a resonant frequency, and obtaining the refractive index of fluids filling the cavity via the shift in resonant frequency.

Resonant cavity integrated into a waveguide for terahertz sensing

An apparatus comprising a parallel plate waveguide (PPWG) comprising two plates separated by a distance that supports a multimode wave, and a transmitter configured to emit a wave having a frequency from about one hundred Gigahertz (GHz) to about ten terahertz (THz) and to couple to one mode of the PPWG. Also disclosed is an apparatus comprising two plates substantially parallel to one another and separated by at least about five millimeters (mm), and an antenna coupled to the two plates and configured to transmit or receive a wave having a frequency from about one hundred GHz to about ten THz. Disclosed is a method comprising polarizing an electromagnetic beam in the first transverse electric (TE) mode with respect to a PPWG comprising two plates, adjusting the diameter of the electromagnetic beam based on the separation between the plates, and sending the electromagnetic beam into the PPWG.

Ultra low loss waveguide for broadband Terahertz radiation

Systems for THz transmission using new types of THz waveguides with low loss, negligible group velocity dispersion and structural simplicity are described herein. The THz system incorporates the use of a waveguide with two or more substantially parallel conductive elements which may enable many new THz sensing applications. It is now possible to direct the THz pulse inside of containers or around corners, where line-of-sight optics are not practical. Moreover, the systems allow use of either radially polarized or linearly polarized THz antennas. The disclosed systems are compatible with existing terahertz generation and detection techniques.

Method and system for transmitting terahertz pulses

A broadband imaging system is disclosed that provides greatly enhanced depth resolution through the use of phase shift interferometry. The system may comprise a transmitter, a splitter, a phase inverter, and a receiver. The transmitter transmits a signal pulse that is split into a measurement pulse and a reference pulse. The measurement pulse is applied to a sample, and a relative phase shift of approximately &pgr; radians is introduced between the measurement pulse and the reference pulse by the phase inverter. The measurement and reference pulses are then recombined to form a combined pulse that is detected by the receiver. The phase inverter may be a simple lens that introduces a Gouy phase shift by passing the measurement or reference pulse through a focal point. In this manner, a background-free measurement is provided, which provides a greatly enhanced sensitivity to small changes in the measurement waveform, regardless of origin.

Interferometric imaging system and method

Providing a compositional image of an object in real time is accomplished by illuminating the object with a waveform comprising pulses of electromagnetic radiation in the terahertz frequency range and measuring the relative time delays of pulses reflected by the object to determine the positions of dielectric interfaces in the object. According to a further embodiment, the waveform includes one or more pulses of terahertz radiation, each pulse having a duration in the range of approximately 10 to 10,000 femtoseconds.

Method and apparatus for terahertz tomographic imaging

A time-domain signal processing system for displaying, classifying, and recognizing temporal and spectral features in terahertz waveforms returned form materials. Specifically, novel techniques are described for classifying and analyzing the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses. Illustratively, a simple geometric picture may be used for the classification of the waveforms measured for unknown gas species and gas mixtures.

Growing community of inventors

Houston, TX, United States of America

Daniel M Mittleman