A semiconductor device includes a semiconductor substrate having a metasurface layer configured with multiple pairs of finger portions in a repeating arrangement. The multiple pairs of finger portions are electrically configurable to modulate a radiation signal received by the semiconductor device. Each pair of finger portions includes first and second members where the first member is doped with a first dopant and the second member is doped with a second dopant being different to the first dopant. Any two adjacent first or second members are configured to be separated by at least deep subwavelength to enable the repeating arrangement.

There is described a terahertz illumination source for terahertz imaging. The terahertz illumination source generally has: a surface; a plurality of terahertz radiation emitting elements mounted to said surface; a plurality of individual beam shaping elements each being optically coupled to a respective one of said terahertz radiation emitting elements; a collective beam shaper optically coupled to at least some of said individual beam shaping elements; and a control signal generator communicatively coupled to said terahertz radiation emitting elements, said control signal generator supplying a plurality of control signals to said terahertz radiation emitting elements, said terahertz radiation emitting elements emitting a plurality of individual terahertz radiation beams being collected and redirected successively by said individual beam shaping elements and said collective beam shaper, said terahertz radiation emitting elements and/or said control signals being configured so that said individual terahertz radiation beams are incoherent with respect to one another.

There is described a terahertz illumination source for terahertz imaging. The terahertz illumination source generally has: a surface; a plurality of terahertz radiation emitting elements mounted to said surface; a plurality of individual beam shaping elements each being optically coupled to a respective one of said terahertz radiation emitting elements; a collective beam shaper optically coupled to at least some of said individual beam shaping elements; and a control signal generator communicatively coupled to said terahertz radiation emitting elements, said control signal generator supplying a plurality of control signals to said terahertz radiation emitting elements, said terahertz radiation emitting elements emitting a plurality of individual terahertz radiation beams being collected and redirected successively by said individual beam shaping elements and said collective beam shaper, said terahertz radiation emitting elements and/or said control signals being configured so that said individual terahertz radiation beams are incoherent with respect to one another.

A photoconductive switch for generating or detecting terahertz radiation (TR) is provided. The photoconductive switch may comprise at least a first and a second pair of electrodes (E.sub.V, E.sub.H, E.sub.GR) on a surface (SS) of a photoconductive substrate, wherein the electrodes of the first pair are separated by a first gap comprising at least a plurality of first rectilinear sections (G.sub.V) extending along a first direction (x) and the electrodes of the second pairs are separated by a second gap comprising at least a plurality of second sections (G.sub.H) extending along a second direction (y), different from the first direction. The photoconductive switch may further comprise a patterned opaque layer (PML) selectively masking portions of the gaps between the electrodes. Methods and devices for generating and detecting terahertz radiation comprising such photoconductive switches are also provided.

A photoconductive antenna has an array of antenna electrodes on or in a photoconductive substrate. The photoconductive substrate is irradiated with light from a pulsed laser via micro-lenses above respective gaps between antenna electrodes. This makes the photoconductive substrate temporarily conductive, causing pulsed electric antenna currents that can be used for transmission of electromagnetic radiation in the Terahertz range. The bias circuit of the antenna is configured to determine voltages applied to the antenna electrodes by capacitive voltage division over a series of successive capacitors, each capacitor being formed by the antenna electrodes of a respective pair of successive ones of the antenna electrodes in the array as plates of the capacitor adjacent to a respective one of the gaps.

A system for modulating a terahertz beam includes a multiferroic nanoparticle heterostructure through which a terahertz beam can be propagated, and means for applying an external direct current (DC) magnetic field to the multiferroic nanoparticle heterostructure and the terahertz beam propagating through it, wherein application of the DC magnetic field modulates one or both of an amplitude and a phase of the terahertz beam.

In example embodiments, a radiation source uses Rydberg states to generate coherent THz radiation (e.g., in the range of 1-20 THz). The radiation source includes a pair of pump lasers (e.g., external-cavity diode lasers (ECDLs)) optically coupled (e.g., by a dichroic mirror and optical fiber) to a heated vapor cell (e.g., a vacuum chamber) holding an atomic species (e.g., rubidium (Rb)). The pump lasers optically pump the atomic species (e.g., Rb) to a predetermined Rydberg state (e.g., the nD.sub.5/2 state), which creates a population inversion between that state (e.g., the nD.sub.5/2 state) and a lower lying Rydberg state (e.g., the (n+1)P.sub.3/2 state). The emission between these two strongly dipole coupled Rydberg states generates coherent THz radiation.

The present invention provides a far-infrared light source capable of reducing the shift in the location irradiated with far-infrared light even when the frequency of the far-infrared light changes. A far-infrared light source according to the present invention is configured so that the variation in the emission angle of far-infrared light in a nonlinear optical crystal when the frequency of the far-infrared light changes is substantially offset by the variation in the refractive angle of the far-infrared light at the interface between the nonlinear optical crystal and a prism when the frequency of the far-infrared light changes

A solid-state device for photo detection, in general, of terahertz radiation is disclosed. One aspect is a detector device comprising a body having a photoconductive material, a first antenna element connected to a first portion of the body, and a second antenna element connected to a second portion of the body. The first antenna element and the second antenna element are arranged to induce an electric field in the body in response to an incident signal. Further, the device has a waveguide arranged to couple light into the photoconductive material via a coupling interface between the waveguide and the body, where the coupling interface faces away from the first portion and the second portion of the body and is closer to the first portion than to the second portion.

A nonlinear fiber interferometer is disclosed suitable for fiber sensor and other applications. A first nonlinear fiber section amplifies probe and conjugate sidebands of a pump through four-wave mixing. A second section introduces a phase shift to be measured, for example from a sensor. A third nonlinear fiber section amplifies with phase-sensitive gain to increase signal-to-noise ratio. Based on phase-sensitive output power of probe and/or conjugate components, the phase shift can be measured. Superior performance can be obtained by balancing gain between the (first and third) nonlinear sections. Non-fiber, for example photonic integrated circuit, embodiments are disclosed. Differential sensing, alternative detection schemes, sensing applications, associated methods, and other variations are disclosed.