An apparatus for generation of coherent terahertz radiation is provided. In one example, the apparatus includes one or more multilayer tunable microcolumns. In turn, a multilayer tunable microcolumn can include a substrate, a bottom electrode, a bottom layer of a ferromagnetic material further comprising a magnon gain medium (MGM) coupled to the bottom electrode, a tunnel junction coupled to the ferromagnetic material, a spin injector coupled to the tunnel junction, a pinning layer coupled to the spin injector, a reference layer coupled to the pinning layer and a top electrode. In one example, a containment cavity encloses at least one of the multilayer tunable microcolumns. In one example, a storage cavity encloses the containment cavity.

One aspect of the present disclosure provides a terahertz-wave detector including a semiconductor substrate, an active element formed on the semiconductor substrate and a first resistive portion electrically connected in parallel with the active element.

This far-infrared spectroscopy device is provided with: a variable wavelength far-infrared light source that generates first far-infrared light; an illuminating optical system that irradiates a sample with the first far-infrared light; a detecting nonlinear optical crystal that converts second far-infrared light into near-infrared light using pump light, said second far-infrared light having been transmitted from the sample; and a far-infrared image-forming optical system that forms an image of the sample in the detecting nonlinear optical crystal. The irradiation position of the first far-infrared light on the sample does not depend on the wavelength of the first far-infrared light.

This far-infrared spectroscopy device is provided with: a variable wavelength far-infrared light source that generates first far-infrared light; an illuminating optical system that irradiates a sample with the first far-infrared light; a detecting nonlinear optical crystal that converts second far-infrared light into near-infrared light using pump light, said second far-infrared light having been transmitted from the sample; and a far-infrared image-forming optical system that forms an image of the sample in the detecting nonlinear optical crystal. The irradiation position of the first far-infrared light on the sample does not depend on the wavelength of the first far-infrared light.

A terahertz-wave generation method of generating a terahertz wave in a direction satisfying a non-collinear phase-matching condition by making pump light incident on a nonlinear optical crystal capable of generating a terahertz wave by optical parametric effect, makes the pump light incident on the nonlinear optical crystal so that a peak excited power density is equal to or greater than a predetermined terahertz-wave lasing threshold and equal to or less than a predetermined laser damage threshold, and an average excited power density, is equal to or less than a predetermined photorefractive effect occurrence threshold, the pump light having a pulse width of 10 ps or more, the pulse width of 1 ns or less, and a repetition frequency of 1 kHz or more.

Acoustically mediated spintronic THz emitters in which sound waves, rather than direct laser pulses, give rise to a spin current in a magnetic material via magnetoelastic coupling are provided. The THz emitters include a metal layer that acts as a light-to-acoustic transducer. Also provided are THz time-domain spectrometers (THz-TDSs) that incorporate the THz emitters.

Acoustically mediated spintronic THz emitters in which sound waves, rather than direct laser pulses, give rise to a spin current in a magnetic material via magnetoelastic coupling are provided. The THz emitters include a metal layer that acts as a light-to-acoustic transducer. Also provided are THz time-domain spectrometers (THz-TDSs) that incorporate the THz emitters.

A terahertz wave lens includes a substrate having a surface provided with an uneven structure that changes a phase of the terahertz wave. The uneven structure includes a plurality of holes that are periodically arranged. The uneven structure includes a plurality of regions where the plurality of holes are arranged. A height of the hole in a thickness direction of the substrate and a width of the pillar differ for each of the regions. Outer end portions of the uneven structure in the thickness direction are located on the same plane.

An optical waveguide apparatus including a first dispersion unit and a separation unit. The first dispersion unit is connected to the separation unit, the first dispersion unit is configured to disperse a frequency component of at least one first optical signal, and the separation unit is configured to separate, into at least one second optical signal based on configuration information, the frequency component that is of the at least one first optical signal and that is dispersed by the first dispersion unit. The separation unit is implemented by a variable optical waveguide, and the variable optical waveguide is an optical waveguide that implements at least one of the following functions based on the configuration information: forming an optical waveguide, eliminating an optical waveguide, and changing a shape of an optical waveguide.

This far-infrared spectroscopy device is provided with: a variable wavelength far-infrared light source that generates first far-infrared light; an illuminating optical system that irradiates a sample with the first far-infrared light; a detecting nonlinear optical crystal that converts second far-infrared light into near-infrared light using pump light, said second far-infrared light having been transmitted from the sample; and a far-infrared image-forming optical system that forms an image of the sample in the detecting nonlinear optical crystal. The irradiation position of the first far-infrared light on the sample does not depend on the wavelength of the first far-infrared light.