An optical sensing system may include a light separation element configured to separate an input light into a plurality of sliced lights and a first resonator configured to receive one sliced light of the plurality of sliced lights. An effective refractive index of the first resonator may be changeable in response to a change in a refractive index of a cladding of the first resonator, a second resonator coupled to the first resonator and a detector configured to measure an intensity of the sliced light, the intensity of the sliced light based on a difference between a resonant wavelength of the first resonator and a resonant wavelength of the second resonator. The difference between a resonant wavelength of the first resonator and a resonant wavelength of the second resonator may be based on the effective refractive index of the first resonator.

Methods and systems using one or more distributed feedback (DFB) lasers for capturing changes in the lasing environment are disclosed. Specifically, a sensor for measuring a measurand, such as pressure or temperature, or changes in a measurand, includes a fiber with at least one core, at least one fiber laser cavity formed by a single fiber grating in the core, wherein the laser operates on at least two modes along at least part of its length. The DFB laser includes a section that is bent into a non-linear shape and at least one pump laser connected to the fiber laser cavity. When the DFB laser experiences a perturbation or measurand change that changes the spacing of the modes, a change in an RF beat note is generated. This beat note can then be measured and related to the measurand change.

A single element thin-film device, a method for producing a thin-film device, a single element for detecting hydrogen absorption, a hydrogen sensor, and an apparatus for detecting hydrogen and to an electro-magnetic transformer comprising such sensor. A thin-film device comprises a substrate, an active sensing layer whose optical properties change depending on hydrogen content, and a protective layer on the active sensing layer.

The present disclosure relates to structures, systems, and methods for characterizing one or more fluorescent particles. At least one embodiment relates to an integrated waveguide structure. The integrated waveguide structure includes a substrate. The integrated waveguide structure also includes a waveguide layer arranged on top of the substrate. The waveguide layer includes one or more excitation waveguides, one or more emission waveguides, and a particle radiation coupler, which includes a resonator element. In addition, the integrated waveguide structure includes one or more sensing sites configured with respect to the one or more excitation waveguides and the one or more emission waveguides such that a fluorescent particle at one of the sensing sites is activated by an excitation radiation transmitted via the one or more excitation waveguides and radiation emitted by the fluorescent particle is coupled into at least one of the emission waveguides by the particle radiation coupler.