Techniques and optically excited light-emitting devices based on phosphors are provided to use phosphor materials which absorb excitation light to emit visible light and include a composite phosphor material including two or more different transition metal compounds that, under optical excitation of the excitation light, emit visible light at spectrally close but different spectral wavelengths or bands that spectrally overlap to produce a desired color.

Techniques and optically excited light-emitting devices based on phosphors are provided to use phosphor materials which absorb excitation light to emit visible light and include a composite phosphor material including two or more different transition metal compounds that, under optical excitation of the excitation light, emit visible light at spectrally close but different spectral wavelengths or bands that spectrally overlap to produce a desired color.

A current-assisted photonic demodulator includes a detection portion having two doped modulation regions and two doped collection regions, lying flush with a first face covered by a dielectric layer. Electrodes pass through the dielectric layer and come into contact with the doped regions. In addition, intermediate electrodes partly pass through the dielectric layer and are spaced apart from the first face by a non-zero distance, each being located, in projection in a main plane, between one of the doped modulation regions and the adjacent doped collection region.

A current-assisted photonic demodulator includes a detection portion having two doped modulation regions and two doped collection regions, lying flush with a first face covered by a dielectric layer. Electrodes pass through the dielectric layer and come into contact with the doped regions. In addition, intermediate electrodes partly pass through the dielectric layer and are spaced apart from the first face by a non-zero distance, each being located, in projection in a main plane, between one of the doped modulation regions and the adjacent doped collection region.

A wavelength conversion device that converts input signal light having a first frequency into output signal light having a second frequency, includes: a control-light generator that outputs first continuous oscillation light and second continuous oscillation light; and a nonlinear optical medium that cross-phase modulates the input signal light with the first continuous oscillation light and the second continuous oscillation light and generates the output signal light, wherein the control-light generator outputs the first continuous oscillation light and the second continuous oscillation light to have polarized waves in directions orthogonal to each other and have a frequency interval equal to a difference between the first frequency and the second frequency and controls, based on intensity of the output signal light, timings of modulation of phases of the first continuous oscillation light and the second continuous oscillation light to be aligned with each other.

A Fourier transform is performed on a first waveform function in a frequency domain, and a second waveform function in a time domain including a temporal intensity waveform function and a temporal phase waveform function is generated. A replacement of the temporal intensity waveform function based on a desired waveform is performed for the second waveform function. The second waveform function is modified so as to bring a spectrogram of the second waveform function close to a target spectrogram generated in advance in accordance with a desired wavelength band. An inverse Fourier transform is performed on the modified second waveform function, and a third waveform function in the frequency domain is generated. Data is generated on the basis of an intensity spectrum function or a phase spectrum function of the third waveform function.

A method for generating a control signal, having at least one frequency component, for an acousto-optical element, from one frequency spectrum having the at least one frequency, or from multiple frequency spectra which together have the at least one frequency, includes the step of obtaining, from the one frequency spectrum or from the multiple frequency spectra, one transmit signal in the time domain in each case via an inverse Fourier transform. The one or the multiple transmit signals are modulated via a single-sideband modulation onto a carrier signal having a carrier frequency in order to obtain one modulated signal in each case. The control signal is obtained as a real part of the one modulated signal or as a consolidation of the real parts of the multiple modulated signals.

A polarization tracking device that tracks polarization fluctuation of light using a Stokes vector, includes: an updating unit configured to express a fluctuation amount of the Stokes vector on a Poincare sphere in an xy plane perpendicular to a travelling direction of a light, wave using a first and a second angles, the first angle being an angle between a direction of an electric field of the light wave and y axis, and the second angle being a phase difference between a component of the optical electric field in a direction of the y axis and a component of the optical electric field in a direction of an x axis; and an application unit configured to rotate the Stokes vector using an inverse polarization rotation matrix expressed with the first and the second angles.

A polarization tracking device that tracks polarization fluctuation of light using a Stokes vector, includes: an updating unit configured to express a fluctuation amount of the Stokes vector on a Poincare sphere in an xy plane perpendicular to a travelling direction of a light, wave using a first and a second angles, the first angle being an angle between a direction of an electric field of the light wave and y axis, and the second angle being a phase difference between a component of the optical electric field in a direction of the y axis and a component of the optical electric field in a direction of an x axis; and an application unit configured to rotate the Stokes vector using an inverse polarization rotation matrix expressed with the first and the second angles.

An optical microphone includes: a light source; a first optical divider dividing light from the light source into reference light and measurement light; a second optical divider dividing the measurement light into N measurement light beams; a first emitter emitting the N measurement light beams from different positions toward a predetermined space; a first light receiver receiving the N measurement light beams having propagated through the space; a third optical divider dividing the reference light into N reference light beams; N optical couplers coupling the N measurement light beams with the N reference light beams on a one-to-one basis; N optical detectors receiving N coupled light beams and each detecting interference between the measurement light beam and the reference light beam in the corresponding coupled light beam; and a controller controlling directionality of sound pickup by performing signal processing on N detection signals from the N optical detectors.