A device using a liquid crystal medium exhibiting an optically isotropic liquid crystal phase, particularly, a blue phase liquid crystal medium for polarized light control application, in which reduction of an effective dielectric constant in a high frequency region is suppressed. A liquid crystal composition contains achiral component T, and has a liquid crystal phase optically exhibiting isotropy, in which achiral component T contains at least one compound selected from the group of compounds represented by formula (1) as a first component, at least one compound selected from the group of compounds represented by formula (2) and formula (3) as a second component, and is used for optical switching for controlling retardation by electric field-induced birefringence.

The present invention relates to a coherent optical transistor device including: first and second coherent optical laser beams from a laser source; wherein the first beam has a relatively higher power/energy than the second beam of at least 2:1; and a permanent sub-wavelength structure in a unitary section into which the first and second beams enter, which permanently modifies a refractive index in both transverse and longitudinal directions; wherein every transverse spatial grating Fourier component in the sub-wavelength structure is phase-shifted by 90 degrees (pi/2) from each of corresponding Fourier components of a spatial interference of the first and second optical beams; and a refractive index profile in the unitary structure in the longitudinal direction is permanently modified, leading to a complete transfer of energy from the first to the second optical beam, resulting in a gain mechanism that results in an amplified signal beam and an inverted signal beam.

A metasurface unit cell for use in constructing a metasurface array is provided. The unit cell may include a ground plane layer comprising a first conductive material, and a phase change material layer operably coupled to the ground plane layer. The phase change material layer may include a phase change material configured to transition between an amorphous phase and a crystalline phase in response to a stimulus. The unit cell may further include a patterned element disposed adjacent to the phase change material layer and includes a second conductive material. In response to the phase change material transitioning from a first phase to a second phase, the metasurface unit cell may resonate to generate an electromagnetic signal having a defined wavelength. The first phase may be the amorphous phase or the crystalline phase and the second phase may be the other of the amorphous phase or the crystalline phase.

A liquid crystal photoelectric apparatus including an upper substrate, a lower substrate, a plurality of alignment layers, and a liquid crystal material is provided. The alignment layers include an upper alignment layer, a lower alignment layer, and at least one intermediate alignment layer. The upper alignment layer has a first orientation direction. The lower alignment layer has a second orientation direction. The at least one intermediate alignment layer has an intermediate orientation direction. The intermediate orientation direction is between the first orientation direction and the second orientation direction. The liquid crystal material includes a plurality of liquid crystal material portions. Each of the liquid crystal material portions is disposed between any adjacent two alignment layers. A manufacturing method of the liquid crystal photoelectric apparatus is also provided.

A pump beam (12) is pre-tilted by subjecting the pump beam to pulse-front-tilting, the thus obtained tilted-pulse-front pump beam is then coupled into the nonlinear optical medium. THz radiation is generated in the optical medium by nonlinear optical processes, in particular by optical rectification, by the pump beam. A pulse-front-tilt of the pump beam satisfying the velocity matching condition of v.sub.p,cs cos()=v.sub.THz,f is induced as a sum of a plurality of pulse-front-tilts separately induced as a partial pulse-front-tilt of the pump beam in subsequent steps. The last step of pulse-front-tilting of the pump beam is performed by coupling the pump beam into the nonlinear optical medium through a stair-step structure (40) formed in an entry surface (51) of the nonlinear optical medium which forms an angle () of a given non-zero size with an exit surface (52) of said nonlinear optical medium.

A high-electron mobility transistor (HEMT) array terahertz wave modulator loaded in a waveguide is provided, which belongs to the technical field of electromagnetic functional devices and focuses on fast dynamic functional devices in the terahertz band. The device comprises a waveguide cavity and a modulation chip. The modulation chip comprises a semiconductor material substrate, a heterostructure material epitaxial layer, an artificial microstructure, and a socket circuit. The applied voltage controls the distribution change of the two-dimensional electron gas in the HEMT, which in turn controls the resonance mode conversion in the artificial microstructure, thereby control the transmission of electromagnetic waves in the waveguide. The modulator has a modulation depth of up to 96% and a modulation rate above 2 GHz. The invention can be realized by using micro-processing technology, and the preparation process is mature and reliable.

Provided is an optical element including: a main body which is formed of a medium capable of transmitting first light and second light having a wavelength longer than that of the first light, in which the main body includes an incident region into which the first light and the second light are incident, in which a gap which is inclined with respect to the incident region and in which a medium having a refractive index with respect to the first light and the second light lower than that of the main body is disposed is provided inside the main body, and in which a gap width from an interface bordering the main body and the gap is larger than a penetration length of an evanescent wave of the first light at the interface and is smaller than a penetration length of an evanescent wave of the second light at the interface.

A wideband terahertz modulator based on gradual openings, which belongs to the technical field of electromagnetic functional devices, includes: a semiconductor substrate; an epitaxial layer provided on the semiconductor substrate; a modulation units array, a positive voltage loading electrode and a negative voltage loading electrode which are provided on the epitaxial layer; wherein each modulation unit in the modulation units array comprises a disconnected H-shaped structure, a metal electrode located below an end of the opening of the disconnected H-shaped structure, and a semiconductor doped heterostructure located below the opening of the disconnected H-shaped structure; wherein in the disconnected H-shaped structures, adjacent modulation units have different opening positions; in a same row, the opening positions are linearly distributed and have a certain slope, and inclination slopes of the opening positions of two adjacent rows are opposite.

A THz laser source includes a first generator suitable for emitting at least one first light emission and one second light emission of frequencies that are multiples of a first reference frequency; a second generator suitable for emitting at least one first light emission and one second light emission of frequencies that are multiples of a second reference frequency different from the first reference frequency; the THz laser source furthermore comprises a nonlinear crystal suitable for forming, from the first light emissions emitted by each of the first and second generators, a THz light emission generated by difference-frequency generation, of frequency comprised between 0.3 THz and 10 THz; and at least one first frequency-stabilizing module allowing the frequency of one of the second emissions emitted by one of the first and second generators to be stabilized to an atomic transition.

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.