Multiplexed reflection and transmission gratings, and methods of their manufacture, are provided that improve uniformity with laser light, that is, reduced banding and other illumination artifacts occurring in waveguides. The mechanism for this can be the multiple reflections between the waveguide reflecting surfaces and the reflection hologram, which promote illumination averaging as beam propagation processes within a waveguide. In some gratings, a beam splitter layer overlapping the multiplexed gratings can be provided for the purposes of reducing banding in a laser-illuminated waveguide. The beam splitter can be provided by one or more dielectric layers. The beamsplitter can have sensitivity to one polarization. The beamsplitter can be sensitive to S-polarization. The beam splitter can be an anti-reflection coating optimized for normal incidence that becomes reflective at high TIR angles when immersed in glass or plastic.

An apparatuses relating generally to a test wafer, processing chambers, and method relating generally to monitoring or calibrating a processing chamber, are described. In one such an apparatus for a test wafer, there is a platform. An optical fiber with Fiber Bragg Grating sensors is located over the platform. A layer of material is located over the platform and over the optical fiber.

Coupled resonators having two resonances are described. A first resonance occurs at the frequency of a pump signal. A second resonance occurs at the frequency of a first Stokes signal. The stop band of the coupled resonators suppresses the second Stokes signal and thus all other higher order Stokes signals. The coupled resonators can be used to more efficiently generate a first Stokes signal having a narrow line width signal.

Aspects described herein include an optical apparatus comprising at least a first Bragg grating of a first stage. The first Bragg grating is configured to transmit a first two wavelengths and to reflect a second two wavelengths of a received optical signal. The optical apparatus further comprises a second Bragg grating of a second stage. The second Bragg grating is configured to transmit one of the first two wavelengths and to reflect the other of the first two wavelengths. The optical apparatus further comprises a third Bragg grating of the second stage. The third Bragg grating is configured to transmit one of the second two wavelengths and to reflect the other of the second two wavelengths.

An optical fiber for converting a Gaussian laser beam into a Bessel laser beam may include a first segment optically coupled to a second segment with a transition region, the first segment having a first outer diameter greater than a second outer diameter of the second segment. The first segment may include a first core portion with a first cladding portion extending around the first core portion. The second segment may include a second core portion with a second cladding portion extending around the second core portion. The optical fiber may have a non-axisymmetric refractive index profile or may be coupled to an end cap with a non-axisymmetric refractive index profile.

An opening and closing detection sensor of the present invention includes a fixed base, a moving base, an optical fiber, and a moving member. The moving base is disposed so as to be movable relative to the fixed base. The optical fiber includes an FBG part where a Bragg wavelength varies responding to an interval between the fixed base and the moving base. The moving member moves between a first position corresponding to either one of an opened state or a closed state of an object and a second position corresponding to the other state. The moving member includes a locking part. The locking part abuts on the moving base between a third position located between the first position and the second position, and the second position, thereby moving the moving base together with the moving member, and moving the moving base in a direction separated from the fixed base.

Shape sensing with a multi-core fiber can achieve high accuracy as well as accommodate small bend radii by measuring signals with peripheral waveguide cores placed at multiple different radial distances from the center axis of the fiber, and computing strain metrics from signals of cores selected based on the respective radial distances and a determination of whether the waveguide cores have strained out of range.

Systems, apparatuses, and methods are described for modifying a beam parameter product of a laser beam. The modified beam parameter product may increase the number of tasks that may be performed using a given laser with its original beam parameter product. By increasing the beam parameter product of a laser, an initial low beam parameter product beam may be used to perform tasks requiring a higher beam parameter product. The beam may be modified to redirect portions of the beam at different angles via one or more non-imaging refracting optical components or by one or more Fiber Bragg gratings.

A device for fluid analysis including an integrated computational element (ICE), a sample cell that optically interacts the ICE with a sample to generate a computation light associated with a characteristic of the sample, and a fiber sensor that receives the computation light and converts the computation light into a heat, is provided. The fiber sensor is coupled with a detector through an optical link, and is configured to return a portion of probe light through the optical link to the detector based on the heat converted. A method for using the device for performing fluid analysis is provided. A system for fluid analysis including at least one device as above is also provided.

A system configured to monitor temperature in a plurality of zones of an aircraft includes an optical fiber with first and second ends, first and second connectors, and a first interrogator. The optical fiber includes a plurality of fiber Bragg gratings disposed in the optical fiber. The first connector is disposed on the first end of the optical fiber and the second connector is disposed on the second end of the optical fiber. The first interrogator is connected to the first connector and includes an optical switch. The optical switch is in optical communication with the first connector of the optical fiber and is configured to selectively block transmission of the optical signal to the optical fiber.