Abstract: 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.

Abstract: A device for use with a source of radiation to provide a THz emission image representing a sample. The device comprises a substrate, a metallic probe having a tip adjacent to the substrate surface and a source of AC bias coupled between the probe tip and substrate. Radiation generated by the source of radiation is incident on the substrate surface in the vicinity of the probe tip and generates THz emission based at least on the AC bias coupled between the probe tip and substrate. A method for providing a THz emission image representing a sample is also provided.

Abstract: A microscope for producing an image of a target using THz radiation. The microscope comprises a source for providing an optical pump pulse and an optical probe pulse; a THz emitter for activation by pump pulse to emit a THz pulse that irradiates the target to form a target-modified THz pulse; a THz detector for modulating the probe pulse with the target-modified THz pulse to create a modulated optical probe pulse characteristic of the target; an optical detection system for modifying and detecting the modulated optical probe pulse and converting the modulated optical probe pulse to electronic information; and a processor for receiving the electronic information and producing an image of the sample using the electronic information. The THz emitter and detector comprise one or more EO crystals. The target is positioned on one of the EO crystals in a near-field of the THz pulse.

Abstract: A method of obtaining a series of images of a three-dimensional object. The method includes the steps of 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 two-dimensional array of parallel rays. The optical detection is an array of detectors such as a CCD sensor.

Abstract: A microscope for producing an image of a target using THz radiation. The microscope comprises a source for providing an optical pump pulse and an optical probe pulse; a THz emitter for activation by pump pulse to emit a THz pulse that irradiates the target to form a target-modified THz pulse; a THz detector for modulating the probe pulse with the target-modified THz pulse to create a modulated optical probe pulse characteristic of the target; an optical detection system for modifying and detecting the modulated optical probe pulse and converting the modulated optical probe pulse to electronic information; and a processor for receiving the electronic information and producing an image of the sample using the electronic information. The THz emitter and detector comprise one or more EO crystals. The target is positioned on one of the EO crystals in a near-field of the THz pulse.

Abstract: An antenna for the mobile electronic device. The antenna includes a first L-shaped element connecting to a second L-shaped element. Both elements are used for sending and receiving signals in a frequency band. Besides, an antenna set includes a first antenna unit and a second antenna unit, which are configured to optimize the superposition of both radiations as isotropic.

Abstract: 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.

Abstract: A system for emitting and detecting terahertz frequency electromagnetic pulses. The system comprises a single transceiver device, which may be an electro-optic crystal or photoconductive antenna, for both emitting and detecting the pulses. A related method comprises using a single transceiver device to both emit and detect electromagnetic terahertz frequency pulses. The transceiver device is excited by a pump pulse to emit a terahertz output pulse, which is modulated with a chopper. An object reflects the terahertz pulse and the reflected pulse is detected in the transceiver using a probe pulse. A lock-in amplifier set to the same frequency of the chopper is used to reduce noise in the signal detected by the transceiver. An image of the object may be created using the intensity or the timing of the peak amplitude of the terahertz pulses reflected from the object.

Abstract: An apparatus and a method for the generation of high-energy terahertz radiation. The apparatus and method function by impinging optical radiation on the surface of a semiconductor substrate, creating a photo-generated dipole emitting terahertz radiation. Because it is desirable to orient the dipole perpendicular to the radiation direction to maximize the power of the terahertz radiation, the surface of the semiconductor is modified to achieve this desirable result. More specifically, three embodiments of the surface modification are disclosed: (1) a grating is created in the top surface of a GaAs semiconductor substrate, (2) an InAs film is formed on a Teflon base to create a grating structure on the semiconductor substrate, and (3) a grating is disposed in the surface of the semiconductor substrate such that the optical radiation engages the substrate at Brewster's angle.

Abstract: An ultrafast all-optical nonlinear switch. The switch has as components a substrate and a material disposed on the substrate. In one embodiment, the material includes a plurality of single-walled carbon nanotubes and a polymer forming a composite. Preferably, the polymer is polyimide. In another embodiment, the material includes a plurality of single-walled carbon nanotubes incorporated into a silica. The nanotube loading in the material is less than about 0.1 wt %. The material is a substantially transparent, third-order nonlinear optical material. The switch has a switching speed of less than 1 picosecond for light with a wavelength of about 1.55 micrometers. Also disclosed is a process for preparing the ultrafast all-optical nonlinear switch.

Abstract: A method of improving spatial resolution of a pump-probe terahertz (THz) imaging system for producing an image of an object. The method provides a chopped optical gating beam focused on a semiconductive layer that is either part of the object or a discrete layer placed over the object. The gating beam is focused on a gating pulse focal spot having a diameter effective to cause measurable modulation in transmission of a THz beam through the semiconductive layer when the gating pulse is on as compared to when the gating pulse is off, creating alternating modulated THz beams for detection and processing. Systems for performing the method in transmission and reflection modes are also described.

Abstract: A method and apparatus for measuring electromagnetic pulses as a function of time. Radiation measurement, including measurement of single-shot, free-space terahertz femtosecond pulses, is realized using an electro-optical modulator in combination with an optical streak camera. This method and apparatus allow measurement of electromagnetic pulses previously unmeasurable due to the time resolution restrictions dictated by the time-frequency correlation.

Abstract: Systems and methods for reconstructing a plurality of images of an object. An exemplary system includes a radiation source adapted to emit radiation at a plurality of frequencies; a lens with frequency-dependent focal length, such as a Fresnel lens, adapted to receive radiation modified by the object and to project onto a fixed image plane a frequency-dependent image of a slice of the object perpendicular to the radiation path; a sensor for capturing the frequency-dependent image of the object; and apparatus for facilitating creation and capture of a plurality of frequency-dependent images of the object at the plurality of frequencies. A system for reconstructing a tomographic image of the object further includes apparatus for assembling the plurality of frequency-dependent images to reconstruct the tomographic image. Methods and systems are described for use in the visible, audible, and THz frequency ranges and with broadband or narrowband radiation sources.

Abstract: Characterization of free-space electromagnetic energy pulses (15) using a chirped optical probe beam is provided. An electro-optic or magneto-optic crystal (14) is positioned such that the free-space radiation and chirped optical probe signal co-propagate, preferably in a co-linear common direction, through the crystal where a temporal waveform of the free-space radiation is linearly encoded onto a wavelength spectrum of the chirped optical probe signal. The temporal waveform of the free-space radiation is then reconstructed using, for example, a dynamic subtraction of the spectral distribution of the chirped optical probe signal without modulation from the spectral distribution of the chirped optical probe signal with modulation by the free-space radiation.

Abstract: A non-contact, free-space method for determining the index of refraction of a thin film at a desired angular frequency. The method includes generating an input desired-frequency pulse and an optically detectable probe pulse. The thin film is moved in and out of the path of the input pulse, creating an output pulse that alternates between a transmitted signal, created when the film intercepts the input pulse path, and a reference signal, created when the sample is outside the input pulse path. The output pulse modulates the probe pulse, which is then detected with a photo detector, and the difference between the transmitted signal and the reference signal is calculated. The above steps are repeated over a plurality of delay times between the input pulse and the probe pulse until a complete field waveform of the differential signal is characterized. The index of refraction is calculated as a function of a ratio between the differential signal for the thin film and the reference signal.

Abstract: Characterization of free-space electromagnetic energy pulses (15) using a chirped optical probe beam is provided. An electro-optic or magneto-optic crystal (14) is positioned such that the free-space radiation and chirped optical probe signal co-propagate, preferably in a co-linear common direction, through the crystal where a temporal waveform of the free-space radiation is linearly encoded onto a wavelength spectrum of the chirped optical probe signal. The temporal waveform of the free-space radiation is then reconstructed using, for example, a dynamic subtraction of the spectral distribution of the chirped optical probe signal without modulation from the spectral distribution of the chirped optical probe signal with modulation by the free-space radiation.

Abstract: An ultrafast all-optical nonlinear switch. The switch has as components a substrate and a material disposed on the substrate. In one embodiment, the material includes a plurality of single-walled carbon nanotubes and a polymer forming a composite. Preferably, the polymer is polyimide. In another embodiment, the material includes a plurality of single-walled carbon nanotubes incorporated into a silica. The nanotube loading in the material is less than about 0.1 wt %. The material is a substantially transparent, third-order nonlinear optical material. The switch has a switching speed of less than 1 picosecond for light with a wavelength of about 1.55 micrometers. Also disclosed is a process for preparing the ultrafast all-optical nonlinear switch.

Abstract: A method of improving spatial resolution of a pump-probe terahertz (THz) imaging system for producing an image of an object. The method provides a chopped optical gating beam focused on a semiconductive layer that is either part of the object or a discrete layer placed over the object. The gating beam is focused on a gating pulse focal spot having a diameter effective to cause measurable modulation in transmission of a THz beam through the semiconductive layer when the gating pulse is on as compared to when the gating pulse is off, creating alternating modulated THz beams for detection and processing. Systems for performing the method in transmission and reflection modes are also described.

Abstract: A non-contact, free-space method for determining the index of refraction of a thin film at a desired angular frequency. The method includes generating an input desired-frequency pulse and an optically detectable probe pulse. The thin film is moved in and out of the path of the input pulse, creating an output pulse that alternates between a transmitted signal, created when the film intercepts the input pulse path, and a reference signal, created when the sample is outside the input pulse path. The output pulse modulates the probe pulse, which is then detected with a photo detector, and the difference between the transmitted signal and the reference signal is calculated. The above steps are repeated over a plurality of delay times between the input pulse and the probe pulse until a complete field waveform of the differential signal is characterized. The index of refraction is calculated as a function of a ratio between the differential signal for the thin film and the reference signal.

Abstract: Characterization of free-space electromagnetic energy pulses (15) using a chirped optical probe beam is provided. An electro-optic or magneto-optic crystal (14) is positioned such that the free-space radiation and chirped optical probe signal co-propagate, preferably in a co-linear common direction, through the crystal where a temporal waveform of the free-space radiation is linearly encoded onto a wavelength spectrum of the chirped optical probe signal. The temporal waveform of the free-space radiation is then reconstructed using, for example, a dynamic subtraction of the spectral distribution of the chirped optical probe signal without modulation from the spectral distribution of the chirped optical probe signal with modulation by the free-space radiation.