UV Sensor Based on Fiber Bragg Grating Covered with Graphene Oxide Embedded in Composite Materials.

Polymer-matrix composites degrade under the influence of UV radiation in the range of the 290-400 nm band. The degradation of polymer-matrix composites exposed to UV radiation is characterized by extensive aging of the epoxy matrix, resulting in deterioration of their mechanical properties. Glass fibers/epoxy resin composites were made by an out-of-autoclave method whereas a fiber optic sensor was placed between different layers of laminates.

Ultra-narrow linewidth DFB-laser with optical feedback from a monolithic confocal Fabry-Perot cavity.

We present a compact, ultra-narrow-linewidth semiconductor laser based on a 780 nm distributed feedback diode laser optically self-locked to a mode of an external monolithic confocal Fabry-Perot resonator. We characterize spectral properties of the laser by measuring its frequency noise power spectral density. The white frequency noise levels at 5 Hz(2)/Hz above a Fourier frequency as small as 20 kHz.

Thermoacoustic optical path length stabilization in a single-mode optical fiber.

We present a simple technique to actively stabilize the optical path length in an optical fiber. A part of the fiber is coated with a thin, electrically conductive layer, which acts as a heater. The optical path length is thus modified by temperature-dependent changes in the refractive index and the mechanical length of the fiber.