144 results about "Thz radiation" patented technology

A fiber-laser-based implementation of a Terahertz source through difference frequency generation (DFG) by nonlinear optical (NLO) crystals is compact, tunable and scalable. A pair of fiber lasers (Q-switched, CW or mode-locked) generate single-frequency outputs at frequencies ω1 and ω2. A fiber beam combiner combines the laser outputs and routes the combined output to a THz generator head where a nonlinear interaction process in the NLO crystal generates THz radiation.

The Smith Purcell effect, in which a beam of electrons passes close to a conducting grating and induces electromagnetic radiation from the grating surface, can be used as a source of THz radiation. A grating composed of negative index metamaterial (NIM) enhances the output of the Smith Purcell source. Of particular interest is the use of a NIM grating in a Smith-Purcell source to provide a tunable coherent CW source of terahertz (THz) radiation.

A method for inspecting a package to identify an object concealed in the package includes passing two beams of THz-radiation through the package. The frequency of THz radiation in one beam is different from that in the other, and the beams are at an angle to each other. Each of the transmitted beams is used to form an image of the package and the object. The absorption coefficient of the object is determined from the two images. The material of the object is determined from the absorption coefficients at the two frequencies. The method is useful for detecting explosive material concealed in baggage.

This invention relates to apparatus and methods for sensing terahertz radiation, in particular over an area, and to terahertz radiation imaging systems. A terahertz radiation sensor, the sensor comprising an optical beam input to receive an optical probe beam, a detector to modulate said probe beam responsive to terahertz radiation, and a photosensitive detector to provide an output responsive to said probe beam modulation. The sensor being configured to provide a first optical path between said optical beam input and said electro-optic detector and to provide a second optical path between said electro-optic detector and said photosensitive detector, and wherein said sensor further comprises a polarizer, said polarizer being located in both said first and said second optical paths. We further describe imaging systems for use with such a probe.

A TeraMOS sensor based on a CMOS-SOI-MEMS transistor, thermally isolated by the MEMS post-processing, designed specifically for the detection of THz radiation which may be directly integrated with the CMOS-SOI readout circuitry, in order to achieve a breakthrough in performance and cost. The TeraMOS sensor provides a low-cost, high performance THz passive or active imaging system (roughly in the range of 0.5-1.5 THz) by combining several leading technologies: Complementary Metal Oxide Semiconductor (CMOS)-Silicon on Insulator (SOI), Micro Electro Mechanical Systems (MEMS) and photonics. An array of TeraMOS sensors, integrated with readout circuitry and driving and supporting circuitry provides a monolithic focal plane array or imager. This imager is designed in a commercial CMOS-SOI Fab and the MEMS micromachining is provided as post-processing step in order to reduce cost. Thus the CMOS transistors and technology provide the sensors as well as the signal processing and additional readout circuitry both in the pixels as well as around the sensor array.

A method of forming a three-dimensional internal image of an object includes illuminating the object with terahertz (THz) radiation and detecting THz radiation that is either transmitted through, reflected from or backscattered from the object. The detected radiation is used to form a series of two-dimensional images of the object at different angles or positions. The recorded two-dimensional images are electronically processed using computer aided tomography (CAT) algorithms to form the three-dimensional image of the object.

A material measurement system (500) includes a THz generator including at least one laser source (111) for emitting optical pulses, the optical pulses coupled to a THz emitter (51) operable for emitting pulsed THz radiation at a sample location on material while being processed (14) by a manufacturing system. A receiver (52) is operable to receive the optical pulses and to detect reflected or transmitted THz radiation from the sample location (14) synchronously with the optical pulses and provide electrical detection signals. Synchronizing optics (112, 113, 114) is operable to receive the optical pulses from said laser and provide the optical pulses to both the receiver (52) and the THz emitter (51). A controller (25) includes at least one processor (87) for receiving the electrical detection signals and providing a processed electrical detection signal, and an analyzer (88) operable to determine at least one, and generally a plurality of properties of the material from the processed electrical detection signal.

Methods to infer the density of defects in high κ dielectric films in a non-contact, non-invasive and non-destructive manner. THz radiation is employed to measure the change in electrical conductivity of the films before and after illumination with visible light, where the visible light photoionizes the defects thereby changing the electrical conductivity and changing the transmission (or reflection) of THz radiation from the films. The disclosed techniques can be employed to make measurements as soon as wafers are fabricated. The technology is applicable to wafers of any size.

A coating facility includes a coating unit for applying a coating layer to a body; and a sensor system for characterizing a coating of the body, the coating including the applied coating layer, in a non-contact manner by use of THz radiation. The sensor system includes a THz system, a processing unit and a positioning system. The THz system includes a light source generating a source light radiation; a flexible first radiation guide cable transmitting the source light radiation; a THz emitter having a THz radiation generator coupled to the light source via the flexible first radiation guide cable for receiving the source light radiation from the light source and adapted for generating outgoing THz radiation from the source light radiation, and a THz optical system for directing the outgoing THz radiation towards the coated body; and a THz detector for detecting incoming THz radiation having interacted with the coating.

A method of obtaining a series of images of a three-dimensional object by transmitting pulsed terahertz (THz) radiation through the entire object from a plurality of angles, optically detecting changes in the transmitted THz radiation using pulsed laser radiation, and constructing a plurality of imaged slices of the three-dimensional object using the detected changes in the transmitted THz radiation. The THz radiation is transmitted through the object as a scanning spot. The object is placed within the Rayleigh range of the focused THz beam and a focusing system is used to transfer the imaging plane from adjacent the object to a desired distance away from the object. A related system is also disclosed.

The invention relates to a broadband Terahertz (THz) radiation generation and detection system and method. THz radiation is generated by optical rectification of an ultrashort pump pulse of a first wavelength having a duration in the picosecond- or sub-picosecond range in a first nonlinear optical crystal. The THz radiation is detected by electro-optic sampling or another appropriate method of a probe beam having a second wavelength in a second nonlinear optical crystal. According to the invention, at least one of the following conditions is fulfilled: a) the first wavelength is different from the second wavelength; b) the material of the first nonlinear optical crystal is different from the material of the second nonlinear optical crystal. This makes it possible to choose for the generation and for the detection process—independent of one another—the combination of wavelengths and nonlinear material and possibly other features of the pump / probe pulses like polarization with the highest efficiency for generation and detection of Terahertz pulses, respectively.

Non-invasive THz spectroscopic apparatus and methods are provided for detecting and / or identifying constituents such as variations in a structural entity where chemical or biological entities can reside. Position dependent scattering of THz radiation is employed to image voids and defects in the internal structure of samples, enabling the determination of contamination, spoilage or readiness of products such as wine in sealed containers.

A method and apparatus for enhanced THz radiation coupling to molecules, includes the steps of depositing a test material near the discontinuity edges of a slotted member, and enhancing the THz radiation by transmitting THz radiation through the slots. The molecules of the test material are illuminated by the enhanced THz radiation that has been transmitted through the slots, thereby producing an increased coupling of EM radiation in the THz spectral range to said material. The molecules can be bio-molecules, explosive materials, or species of organisms. The slotted member can be a semiconductor film, a metallic film, in particular InSb, or layers thereof. THz detectors sense near field THz radiation that has been transmitted through said slots and the test material.

A thermally powered source of IR or THz radiation combines low dimension nano-scale oscillators such as nano-wires and nano-tubes with micro-scale photonic crystal resonant defect cavities for efficient generation, coupling and transmission of electromagnetic radiation. The oscillators have M=0, 1 or 2 resonant dimensions on a micro-scale (approximately 1 um to approximately 1 mm) to emit radiation having a local peak at a desired wavelength in the IR or THz regions. The oscillators have at least one non-resonant dimension on a nano-scale (less than approximately 100 nm) to suppress vibration modes in that dimension and channel more thermal energy into the local peak. The photonic crystal defect cavities have N=1, 2 or 3 (N>M) resonant dimensions on the microscale with lengths comparable to the length of the oscillator and the desired wavelength to exhibit a cavity resonant that overlaps the local peak to accept and transmit emitted radiation. The energy from multiple oscillator / defect cavities pairs can be collected and transmitted by an internal waveguide or external mirrors and lens to a specified location where it is output. To improve coupling efficiency, the oscillators and defect cavities preferably exhibit a physical symmetry so that they are substantially “mode matched”. The integration of nano-scale emitters with micro-scale photonic crystal defect cavities creates a new class of metamaterials that more efficient generate radiation.

A method for detecting specific associations between a tethered molecule and an untethered target molecule. The method comprises (1) selecting a tethered molecule; (2) alternately impinging THz radiation onto the tethered molecule and onto a sample including the tethered and untethered target molecules; (3) detecting the radiation impinged on the tethered molecule to form a reference signal and the radiation impinged on the sample to form a sample signal; and (4) comparing the reference signal with the sample signal to generate a specimen signal indicative of an association between the selected tethered and target molecules. The method will detect whether a selected tethered molecule and the desired target exhibit any affinity or, in cases where the affinity is known, will detect the presence of the target molecule in a sample. Also provided is an apparatus for detecting specific associations between a tethered molecule and an untethered target molecule.

An in-situ time domain spectroscopy (TDS)-based method (200) for non-contact characterization of properties of a sheet material while being produced by a manufacturing system (700). A time domain spectrometry system (100) and calibration data for the system is provided. The calibration data includes data for transmitted power through or reflected power from the sheet material as a function of a moisture content of the sheet material. At least one pulse of THz or near THz radiation from a transmitter (111) is directed at a location on a sheet material sample (130) while being processed by the manufacturing system (700). Transmitted or reflected radiation associated with at least one transmitted or reflected pulse from the sample location is synchronously detected by a detector (110) to obtain the sample data. The sample data, which is coincident data, is processed together with the calibration data (207, 208, 209) to determine at least one, and generally a plurality of properties of the sheet material sample (130) selected from caliper, basis weight and moisture content.

A technique is provided for examining a subject. The technique includes illuminating at least a part of the subject with THz radiation and detecting THz radiation reflected and / or transmitted from the illuminated part and incident upon a detector array by measuring change in capacitance corresponding to the incident THz radiation.

A solution for analyzing characteristics of compounds and materials (e.g., chemical composition, specific quantity, thickness, etc.) via THz time domain spectrometry is disclosed. In one embodiment, a spectrometry system includes: a portable housing including: a portable power source; a laser source connected to the portable power source; a terahertz (THz) emitter located within the portable housing and optically connected to the laser source via an optical array including a rotary delay stage, the THz emitter configured to emit THz radiation directed to interact with a material sample; a detector optically connected to the optical array and configured to obtain waveform data from the interaction between the THz radiation and the material sample; and a computing device communicatively connected to the detector and configured to process the waveform data to determine a characteristic of the material sample.

Provided are systems and methods to generate single-cycle THz pulses from a few tens of nanometers thin layer of split ring resonators (SRRs) via optical rectification of femtosecond laser pulses. The emitted THz radiation, with a spectrum ranging from about 0.1 to 4 THz, arises exclusively from pumping the magnetic-dipole resonance of SRRs around 200 THz. This resonant enhancement, together with pump polarization dependence and power scaling of the THz emission, underpins the nonlinearity from optically induced circulating currents in SRRs, with a huge effective nonlinear susceptibility of 0.8×10−16 m2 / V that far exceeds surface nonlinearities of both thin films and bulk organic / inorganic crystals and sheet nonlinearities of non-centrosymmetric materials such as ZnTe.

The invention relates to a surface sensor (100, 200), comprising a frequency-selective surface with periodically arranged THz structures (1), in particular THz resonance structures (1) which are sensitive to THz radiation, a polarization axis (3) being associated with each structure. In order to improve remote field characteristics, the invention provides for a THz structure (1) to be configured asymmetrically, and a group of two or more THz structures (1) to have essentially centrosymmetrically aligned polarization axes (3) for forming a unit cell.

A detector of terahertz (THz) energy includes a MOSFET having an extended source region, and a channel region depleted of free carriers, which MOSFET operates in a sub-threshold voltage state and has an output that is an exponential function of THz energy supplied to the gate.

A system and a method for generating terahertz (THz) radiation are provided. The system includes a photonic crystal structure comprising at least one nonlinear material that enables optical rectification. The photonic crystal structure is configured to have the suitable transverse dispersion relations and enhanced density photonic states so as to allow THz radiation to be emitted efficiently when an optical or near infrared pulse travels through the nonlinear part of the photonic crystal.

The invention relates to a device for generating terahertz waves, in particular to a device for generating tunable narrowband terahertz waves by using optical difference frequency. The device comprises a pumping light source, an idler frequency light source, a nonlinear crystal and a controller. The nonlinear crystal is arranged on the light path of the co-linear beam emitted by the pumping light source and the idler frequency light source. The controller is connected with the idler frequency light source and the nonlinear crystal respectively. In order to solve the technical problem of generating THz radiation by using optical means in the background technology, the invention provides the device for generating tunable narrowband terahertz waves by using optical difference frequency. The device with simple and compact structure is operated and debugged easily. The narrowband THz waves are output quickly and continuously, and are tunable; and the output stability of the THz waves is high.

The invention discloses a novel orthogonal-polarization dual-wavelength laser which belongs to a novel laser and is a dual-wavelength continuous pulse laser or a dual-wavelength repetition-rate pulse laser realizing mutual orthogonality of a horizontal polarized wavelength 1 and a vertical polarized wavelength 2 in polarization directions by adopting an anisotropic neodymium-doped laser crystal with a multichannel transition property. The laser device comprises the anisotropic neodymium-doped laser crystal, such as Nd:YAlO3, Nd:YVO4, Nd:YLF or Nd:GdVO4 and other crystals, a pumping system and an optical resonant cavity, wherein the pumping system is used for pumping the laser crystal to enable active ions (Nd<3+> ions) in the laser crystal to form distribution for population inversion; the optical resonant cavity is used for the resonation of dual-wavelength radiation of the horizontal polarized wavelength 1 and the vertical polarized wavelength 2 of the active ions in transmission emission; and finally, orthogonal-polarization dual-wavelength laser of the horizontal polarized wavelength 1 and the vertical polarized wavelength 2 are simultaneously outputted in the same light path both by the same output coupling mirror. The orthogonal-polarization dual-wavelength laser provides a novel laser source and a novel technical approach to acquisition of high-power, high-coherence or difference-frequency (THz radiation waves) laser, can broaden the application of dual-wavelength laser, and has a broad application prospect and use values in the fields of non-linearity frequency conversion, fiber-optic communication and the like.

A method of generating THz radiation includes the steps of generating optical input radiation with an input radiation source device (10), irradiating a first conversion crystal device (30) with the optical input radiation, wherein the first conversion crystal device (30) is arranged in a single pass configuration, and generating the THz radiation having a THz frequency in the first conversion crystal device (30) in response to the optical input radiation by an optical-to-THz-conversion process, wherein a multi-line frequency spectrum is provided by the optical input radiation in the first conversion crystal device (30), and the optical-to-THz-conversion process includes cascaded difference frequency generation using the multi-line frequency spectrum. Furthermore, a THz source apparatus being configured for generating THz radiation and applications thereof are described.

A method of large-scale active THz imaging using a combination of a compact high power THz source (>1 watt), an optional optical system, and a camera for the detection of reflected or transmitted THz radiation, without the need for the burdensome power source or detector cooling systems required by similar prior art such devices. With such a system, one is able to image, for example, a whole person in seconds or less, whereas at present, using low power sources and scanning techniques, it takes several minutes or even hours to image even a 1 cm×1 cm area of skin.