In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

The disclosed embodiments generally relate to extruding multiple layers of micro- to nano-polymer layers in a tubular shape. In particular, the aspects of the disclosed embodiments are directed to a method for producing a Bragg reflector comprising co-extrusion of micro- to nano-polymer layers in a tubular shape.

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.

A high backscattering optical fiber comprising a perturbed segment in which the perturbed segment reflects a relative power such that the optical fiber has an effective index of n.sub.eff, a numerical aperture of NA, a scatter of R.sub.p.fwdarw.r.sup.(fiber), a total transmission loss of .sub.fiber, an in-band range greater than one nanometer (1 nm), a center wavelength (.sub.0) of the in-band range (wherein 950 nm<.sub.0<1700 nm), and a figure of merit (FOM) in the in-band range. The FOM>1, with the FOM being defined as:

[00001]$\mathrm{FOM}=\frac{R_{p.fwdarw.r}^{\left(\mathrm{fiber}\right)}}{{{}_{\mathrm{fiber}}\left(\frac{\mathrm{NA}}{2.Math.n_{\mathrm{eff}}}\right)}^2}.$

A scour monitoring system may provide a housing that is separated into multiple segments that are fluidically isolated from each other. The scour monitoring system may be position adjacent to a structure to be monitored for bridge scouring. Each of the segments may provide a water-swellable material positioned near or in contact with a fiber Bragg grating (FBG) cable. If water penetrates a segment, the water-swellable material may expand to deform the FBG cable. The wavelength of the FBG cable may be monitored periodically for changes, thereby providing moisture detection when a change in wavelength is detected.

A multi-channel receiver optical sub assembly module for a fiber Bragg grating sensor according to an embodiment of the present invention includes a housing, a connection socket, an optical bench, a thermoelectric cooler, an arrayed waveguide grating chip, a photodiode array disposed on the optical bench and including a plurality of photodiode chips connected to the optical channels of the arrayed waveguide grating chip, and a printed circuit board which is connected to the other side of the housing while passing through the other side of the housing, of which a portion of a body is disposed on the optical bench, and which is connected to the photodiode array.

Fiber Bragg grating interrogation and sensing used for strain and temperature measurements. A simple, broadband light source is used to interrogate one or more fiber Bragg grating (FBG). Specifically, a packaged LED is coupled to fiber, the light therefrom is reflected off a uniform FBG. The reflected light is subsequently analyzed using a filter and a plurality of Si photodetectors. In particular, the filter is a chirped FBG or an optically coated filter, in accordance with some embodiments. Measurement analysis is performed by ratio of intensities at the plurality of detectors, at least in part.

An optical system adapted to detect an object including a beam splitting and combing element, a catheter, a focusing element, a deformation detecting module, and an object detecting module is provided. The catheter sleeves outside an optical fiber, and the optical fiber has at least one fiber Bragg gratings. The deformation detecting module and the object detecting module are coupled to the beam splitting and combing element. A first light is reflected by the at least one fiber Bragg gratings and then transmitted to the deformation detecting module. A second light is transmitted to and reflected by the object, so as to be transmitted to the object detecting module. A first wavelength range of the first light is different from a second wavelength range of the second light.

A reflector includes a gain fiber and a periodic refraction structure unit. The gain fiber has a core doped with a rare earth element. The periodic refraction structure unit includes a high-refractive-index region that has a predetermined width, that is formed at a predetermined spacing along an optical axis direction of the gain fiber, that is formed across an entire section of the core that is orthogonal to the optical axis of the core, and that has a first refractive index, and a low-refractive-index region that is formed adjacent to the high-refractive-index region, that has a width equal to the predetermined spacing, and that has a second refractive index lower than the first refractive index. A width d.sub.i of an i.sup.th periodic structure of refractive index in the periodic refraction structure unit is given by the equation d.sub.i=H.sub.i.Math.(/(2.Math.n.sub.i))+/(4.Math.n.sub.i).

Fiber Bragg grating interrogation and sensing used for strain and temperature measurements. A simple, broadband light source is used to interrogate one or more fiber Bragg grating (FBG). Specifically, a packaged LED is coupled to fiber, the light therefrom is reflected off a uniform FBG. The reflected light is subsequently analyzed using a filter and a plurality of Si photodetectors. In particular, the filter is a chirped FBG or an optically coated filter, in accordance with some embodiments. Measurement analysis is performed by ratio of intensities at the plurality of detectors, at least in part.