The present invention provides a method for realizing high stability of micro-nano optical fiber sagnac loop output by means of filter mode control, and belongs to the field of photoelectric detection technologies. In the present invention, the optical filter is combined with the micro-nano optical fiber Sagnac interference structure so as to control the Sagnac in-loop working mode by use of the mode selection characteristics of the filter. In this way, the interference mode is suppressed to better concentrate energy on the working mode, thereby improving the spectrum output uniformity and stability of the Sagnac loop. Further, the reflection and transmission modes of the optical filter do not participate in interference spectrum output and thus the performance of the system will not be affected. By designing and changing the parameters of the optical filter, the output characteristics of the interferometer can be dynamically controlled.

A bending detecting system includes a light guide, a first grating and a light detector. The light guide has elongated shape and is configured to guide an incident light in a propagating direction. The light guide includes a core and a cladding disposed around the core. The first grating is disposed in a boundary area, the boundary area including an outer surface of the core, and an adjacent area that is adjacent to the outer surface. The first grating includes a first periodic structure along the propagating direction with a first pitch, and is configured to generate a first diffracted light from the incident light. The light detector is configured to detect the first diffracted light from the first grating, and detect a bending of the light guide based upon an optical feature amount of the first diffracted light.

A system for detecting a fire or overheating event includes a heat detector, an optical fiber, a photodetector, and a processing unit. The pneumatic heat detector includes a sealed chamber sealed with a diaphragm having an initial position, and the optical fiber is in operable communication with the diaphragm. The optical fiber includes a Fiber Bragg Grating (FBG). The optical signal generator is configured to emit an optical signal with into the optical fiber. The photodetector is configured to receive a reflected optical signal from the FBG. The processing unit is configured to correlate the reflection wavelength of the reflected optical signal with a temperature of the heat detector.

A method for fabricating three-dimensional structures. In-flight heating, evaporation, or UV illumination modifies the properties of aerosol droplets as they are jetted onto a target surface. The UV light at least partially cures photopolymer droplets, or alternatively causes droplets of solvent-based nanoparticle dispersions to rapidly dry in flight, and the resulting increased viscosity of the aerosol droplets facilitates the formation of free standing three-dimensional structures. This 3D fabrication can be performed using a wide variety of photopolymer, nanoparticle dispersion, and composite materials. The resulting 3D shapes can be free standing, fabricated without supports, and can attain arbitrary shapes by manipulating the print nozzle relative to the target substrate. Multiple materials may be mixed and deposited to form structures with compositionally graded material profiles, for example Bragg gratings in a light pipe or optical fiber, optical interconnects, and flat lenses.

A measurement system for assisting in guiding an elongated medical device in a body is described. The measurement system comprises a multicore fiber for insertion into an elongated medical device such that a position of the tip of the multicore fiber corresponds with a position near the tip of the elongated medical device, the multicore fiber comprising a plurality of cores, and a measurement device being adapted for determining, based on the optical signals measured from the multicore fiber, a known shape applied to the multicore fiber, and for deriving based thereon, a length of the portion of the multicore fiber that has been introduced in the body or a position of the multicore fiber in the body.

A compact, wavelength-stabilized laser source is provided by utilizing a specialty gain element (i.e., formed to include a curved waveguide topology), where a separate wavelength stabilization component (for example, a fiber Bragg grating (FBG)) is used one of the mirrors for the laser cavity. That is, the FBG takes the place of the physical “front facet” of the gain element, and functions to define the laser cavity in the first instance, while also utilizing the grating structure to impart the desired wavelength stability to the output from the packaged laser source. As a result, the FBG is disposed within the same package used to house the gain element and provides a wavelength-stabilized laser source in a compact form.

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.

Optical structures, such as antireflective structures or Bragg gratings, may include multiple layers of high-index and low-index materials. The low-index materials may be approximately a quarter-wavelength in thickness (e.g., with respect to a center wavelength of incident light) and may include a nanovoided material. The high-index material may have a thickness of a half-wavelength and may include an oxide. The nanovoided material may include about 10% to 90% nanovoids by volume and may have an average index of refraction of about 1.05 to about 1.2. The antireflective structures or Bragg gratings may include multiple layers that can be optimized for layer count, thicknesses, and refractive indices to provide a reflectance below a given threshold for incident light of a given angular range. Various other methods, systems, apparatuses, and materials are also disclosed.

There is described a method of fabricating an optical fiber device, the method comprising: positioning longitudinal portions of a plurality of optical fibers alongside each other in a given geometrical relationship, depositing liquid coating material around the longitudinal portions of the plurality of optical fibers; and the liquid coating material setting up around the longitudinal portions of the plurality of optical fibers thereby maintaining said given geometrical relationship along the longitudinal portions.

A waveguide display includes a plurality of grating layers, the plurality of grating layers characterized by two or more different base refractive indices and including a set of volume Bragg gratings (VBGs). Each VBG of the set of VBGs is configured to diffract display light in a different respective field-of-view (FOV) and wavelength range. The set of VBGs includes a plurality of groups of VBGs. VBGs in each respective group of the plurality of groups of VBGs are characterized by a same grating period and include at least one VBG in each grating layer of the plurality of grating layers.