Abstract: An optical delay line for use with an optical source including input/output optics optically coupled to the optical source and a curved mirror with a reflective surface that is centered about an evolute curve of the delay line to retro-reflect light traveling along a delay line beam path tangent to the edge of the evolute curve. The input/output optics direct light from the optical source along the delay line beam path and direct delayed light from the delay line beam path out of the optical delay line along an output beam path. The input/output optics and/or the curved mirror rotate about the evolute curve at a selected angular speed. The reflective surface has a curvature based on a parametric curve that is calculated from the evolute curve such that the delay of the delay line varies according to a predetermined function as the input/output optics and/or the curved mirror rotate.

Abstract: A broad bandwidth detector to measure intensity information of terahertz (THz) frequency pulses. The detector includes: coupling optics coupled to a coherent optical source; a GaSe substrate aligned such that the probe beam path intersects a first surface at a phase-matching angle; a polarization detector aligned in the probe beam path; and calculation means coupled to the polarization detector. The coupling optics direct the probe optical beam along a beam path that is substantially collinear with the pulse beam path of the THz frequency pulses. The polarization of the probe optical beam is varied based on interactions between the probe optical beam and the THz frequency pulses within the GaSe substrate. The polarization detector detects the varied polarization of the probe optical beam. The calculation means determine the intensity information of the THz frequency pulses based on the detected probe polarization of the probe optical beam.

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: 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 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 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.