A terahertz device includes a first waveguide, which is a plasmonic waveguide, having a first core with a nonlinear material, such as a ferroelectric material, and having a cladding with a first cladding portion including, at a first interface with the first core, a first cladding material that is an electrically conductive material. The terahertz device can include an antenna having a first and a second arm (for receiving or for emitting or for both, receiving and emitting electromagnetic waves in the terahertz range); a first and a second electrode arranged close to the first waveguide.

A method includes depositing a crystalline magnesium oxide (MgO) seed layer directly on an amorphous insulating cladding layer by a physical vapor deposition (PVD) process, and depositing a crystalline electro-optic layer directly on the crystalline MgO seed layer.

An electro-optical device is fabricated on a semiconductor-on-insulator (SOI) substrate. The electro-optical device comprises a silicon dioxide layer, and an active layer having ferroelectric properties on the silicon dioxide layer. The silicon dioxide layer includes a first silicon dioxide layer of the SOI substrate and a second silicon dioxide layer converted from a silicon layer of the SOI substrate. The active layer includes a buffer layer epitaxially grown on the silicon layer of the SOI substrate and a ferroelectric layer epitaxially grown on the buffer layer. The electro-optical device further comprises one or more additional layers over the active layer, and first and second contacts to the active layer through at least one of the one or more additional layers. Methods of fabricating the electro-optical device are also described herein.

An optical device that includes at least one magnetic element including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer; a substrate; and a waveguide is provided, wherein the waveguide and the magnetic element are located on or above the substrate, and wherein at least some of light propagating in the waveguide is applied to the magnetic element.

An initial change and a secular change in an optical characteristic and a high frequency characteristic in a case where an optical modulator is mounted in a package of an optical transmission apparatus are suppressed while improving a space utilization rate in the package of the optical transmission apparatus. An optical modulator that is electrically connected to an electric circuit configured on a circuit board, includes a package that houses an optical modulation element, in which the package has, on a bottom surface facing the circuit board, a plurality of first protruding bodies protruding from the bottom surface.

An optical phase shifter according to an embodiment for achieving the object of the present disclosure includes a first semiconductor layer formed on a substrate, a second semiconductor layer having opposite polarity to the first semiconductor layer, an insulating layer formed between the first semiconductor layer and the second semiconductor layer, and including ferroelectrics, a first electrode connected to the first semiconductor layer, and a second electrode connected to the second semiconductor layer. According to an embodiment, the introduction of ferroelectric materials to a semiconductor-insulator-semiconductor (SIS) optical phase shifter brings about improvement in charge collection efficiency resulting from the negative capacitance effect, thereby achieving higher phase modulation efficiency and lower power consumption. Additionally, it is possible to realize a new structure of optical switch or modulator device through design changes of the type of ferroelectrics and the structural variables.

A terahertz device includes a first waveguide, which is a plasmonic waveguide, having a first core with a nonlinear material, such as a ferroelectric material, and having a cladding with a first cladding portion including, at a first interface with the first core, a first cladding material that is an electrically conductive material. The terahertz device can include an antenna having a first and a second arm (for receiving or for emitting or for both, receiving and emitting electromagnetic waves in the terahertz range); a first and a second electrode arranged close to the first waveguide.

An initial change and a secular change in an optical characteristic and a high frequency characteristic in a case where an optical modulator is mounted in a package of an optical transmission apparatus are suppressed while improving a space utilization rate in the package of the optical transmission apparatus. An optical modulator that is electrically connected to an electric circuit configured on a circuit board, includes a package that houses an optical modulation element, in which the package has, on a bottom surface facing the circuit board, a plurality of first protruding bodies protruding from the bottom surface.

There is provided an optical signal processing device that generates a mask function in an optical domain to enable high-speed RC processing. For light emitted from a laser light source, an optical modulator modulates at a modulation period at least one of the intensity and phase values of the optical electric field. Thereby, the light emitted from the laser light source becomes an input signal. The input signal is entered into an optical FIR filter unit. For the input signal, the term corresponding to the mask function is multiplied at the optical FIR filter unit and weighted. Thereby, the input signal is converted into an input signal modulated. The modulated input signal enters via an optical coupler, an optical circulation circuit which is loaded with a variable attenuator and a nonlinear response element. The circulating optical signal is branched into two by an optical coupler. One branched light is converted into an intermediate signal at an optical receiver. The intermediate signal is computed by a formula at an electric signal processing circuit, and thereby, the operation as RC can be performed.

An electro-optic element includes a first waveguide, which is a plasmonic waveguide, including a first core having a ferroelectric material and a cladding having a first cladding portion. The first cladding portion includes, at a first interface with the ferroelectric material, a first cladding material. The electro-optic element includes a first and a second electrode for producing an electric field in the ferroelectric material when a voltage is applied between the first and second electrodes, for modulating a real part of a refractive index of the ferroelectric material. The element includes, in addition, a crystalline substrate on which the ferroelectric material is epitaxially grown with zero or one or more intermediate layers present between the substrate and the ferroelectric material. The element may have a second waveguide, which is a photonic waveguide, including for enabling evanescent coupling between the first and second waveguides.