A frequency modulation demodulator based on fiber grating sensor array comprises: a laser, radio frequency signal source, acousto-optic modulator, delay fiber pair, Mach-Zehnder modulator, optical filter, optical amplifier, optical isolator, circulator, fiber grating sensor array, photodetector and data acquisition card. By the cooperation of delay fiber pair and the fiber grating, the reflected optical pulses of the two gratings (the front grating and the back grating) are overlapped in the time domain to form interference, and thereby achieving multi-point array interference demodulation.

A Mach-Zehnder optical modulator creates a first driving signal to be applied to a first section, and a second driving signal to be applied to a second section, and includes a generator, an optical modulator, and a setting unit. The generator generates a first dither signal and a second dither signal. The optical modulator optical modulates an optical signal into a quaternary or more value optical modulation signal by applying the first driving signal superimposed by the first dither signal, and by applying the second driving signal superposed by the second dither signal. The setting unit sets, when a length of the second section is n times as long as the first section, the first dither signal and the second dither signal to have a same phase, and sets such that an amplitude of the first dither signal is n times as large as that of the second dither signal.

A sensing system for characterizing analytes of interest in a sample comprises a photonic integrated circuit with an integrated interferometer. The integrated interferometer is configured for spectroscopic operation. The integrated interferometer comprises at least a sensing arm and a reference arm, both the sensing arm and the reference arm having an exposable segment available for interaction with the sample, whereby the exposable segment of the reference arm has an optical path length which is smaller than twice the optical path length of the exposable segment of the sensing arm. The exposable section of the sensing arm is selective to the analyte of interest, whereas the exposable section of the reference arm is not selective to the analyte of interest.

An optical semiconductor device comprises a semiconductor substrate, an optical 90-degree hybrid circuit provided on the substrate, a plurality of input optical waveguides provided on the substrate, and a plurality of output optical waveguides provided on the substrate. The plurality of input optical waveguides is optically coupled to input ends of the optical 90-degree hybrid circuit. The plurality of output optical waveguides is optically coupled to output ends of the optical 90-degree hybrid circuit. Each of the plurality of input optical waveguides includes a first curving portion and a first straight portion adjacent to the first curving portion, and each of the plurality of output optical waveguides includes a second curving portion. A central axis of the first curving portion is inwardly offset with respect to a central axis of the first straight portion, and a central axis of the second curving portion follows a raised sine curve.

An optical demultiplexer is disclosed that separates light including a plurality of wavelengths into light of respective wavelengths. Unit circuits are cascaded in a tree structure. In optical demultiplexer components having the same structure, a combination of arm length differences in waveguide pairs is the same with respect to the N1 Asymmetric Mach-Zehnder interferometers in which the phase shifters are arranged, where N equals number of 22 couplers. In three of the optical demultiplexer components in at least one of the unit circuits, N is three or more. Each of control circuits controls the phase shifters arranged in a corresponding optical demultiplexer component of a corresponding unit circuit in order to increase or decrease a value of a function having, as an argument, a power value acquired by a monitor from among monitors arranged at four optical waveguides at an output side of the corresponding unit circuit.

A single mode waveguide with a straight portion and a curved portion, the curved portion having the shape of an adiabatic bend. The single mode waveguide has a curved portion that is shaped according to an adiabatic bend, with a curvature that varies continuously, and that vanishes at a point at which the curved portion is contiguous with a straight portion of the waveguide. The absence of curvature discontinuities avoids the coupling, within the waveguide, of optical power from a fundamental mode into a higher order mode and the curvature of the curved portion results in attenuation of optical power, in higher order modes, that may be coupled into the waveguide at either end.

A system may include a polarization rotator combiner. The polarization rotator combiner may include a first stage, a second stage, and a third stage. The first stage may receive a first component of light with a TE00 polarization and a second component of light with the TE00 polarization. The first stage may draw optical paths of the first and second components together. The second stage may receive the first component and the second component from the first stage. The second stage may convert the polarization of the second component from the TE00 polarization to a TE01 polarization. The third stage may receive the first component and the second component from the second stage. The third stage may convert polarization of the second component from the TE01 polarization to a TM00 polarization. The third stage may output the first component and output the second component.

A Mach-Zehnder optical modulator creates a first driving signal to be applied to a first section, and a second driving signal to be applied to a second section, and includes a generator, an optical modulator, and a setting unit. The generator generates a first dither signal and a second dither signal. The optical modulator optical modulates an optical signal into a quaternary or more value optical modulation signal by applying the first driving signal superimposed by the first dither signal, and by applying the second driving signal superposed by the second dither signal. The setting unit sets, when a length of the second section is n times as long as the first section, the first dither signal and the second dither signal to have a same phase, and sets such that an amplitude of the first dither signal is n times as large as that of the second dither signal.

A broadband light source apparatus, and corresponding method, includes a broadband light source configured to provide source light with a source wavelength spectrum having a centroid thermal sensitivity. The apparatus also includes a broadband optical filter characterized by a filter spectrum that has one or more spectral characteristics and a thermal sensitivity with magnitude and sign. The filter is configured to receive the source light and to deliver broadband output light with an output spectrum that is a function of the source and filter spectra and has an output centroid wavelength. The spectral characteristics and the magnitude and sign of the thermal sensitivity of the filter are configured to minimize a thermal sensitivity of the output centroid wavelength. The filter can be configured in view of a particular source spectrum to stabilize output centroid wavelength and maximize total output power passively with respect to ambient temperature fluctuations.

The invention relates to an optoelectronic switch comprising: a Mach-Zehnder interferometer (10); a switching device (20) comprising: at least two thermo-optical phase-shifters (21a, 21b), and a switching module (22) designed to apply a continuous signal, referred to as switching signal, of constant intensity to the thermo-optical phase-shifters (21a, 21b); at least two electro-refractive phase-shifters (23a, 23b), and a compensation module (24) designed to apply a transient signal, referred to as compensation signal, of variable intensity to the electro-refractive phase-shifters (23a, 23b).