Technology
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The Proximion core competence lies within the manufacturing of tailor made Fiber Bragg Gratings. Proximion holds a wide portfolio of patents and innovative FBG based products, developed to a level where they are immediately useful to our customers. A view of the ultraviolet fringe pattern induced in the core of the fiber.
A fiber Bragg grating can, in its simplest context, be seen as an optical filter where a part of the incident light is either being transmitted or reflected. Since the grating is written in the actual core of the fiber it interacts with the light being transmitted. A grating is generated by exposing the core, typically no more than 5 µm in diameter (i.e. a tenth of the diameter of a normal human body-hair) of a specially prepared optical fiber to a fringe pattern of ultraviolet light. The ultraviolet light will locally induce a change in the refractive index of the core. A change in refractive index will be seen as a tiny mirror by the light trying to pass through the grating, and a small portion will be reflected. By generating many of these local mirrors in sequence at well defined distances, an optically resonant cavity is produced. By tuning the distance and amplitude between the mirror elements, the filter characteristics (e.g. the wavelengths and amount of reflected light) can also be tuned. Proximion’s versatile and proprietary grating writing technology utilizes a two-beam interferometer to create the fringe pattern of ultraviolet light used for inducing the change of refractive index. A highly accurate motion controller can sequentially add up these fringe patterns with sub nanometer precision over long distances.
Two ultraviolet laser beams interfere, resulting in a fringe pattern. By accurately controlling the motion of the fiber many successive fringe patterns can be added into very long gratings
By actively controlling the period of the fringe pattern basically any type of FBG can be generated. Grating characteristics such as wavelength range, reflection and dispersion compensation characteristics are easily controlled via the exposure SW. Proximion’s unique technology is used in a variety of dispersion compensation products like continuous and channelized fixed dispersion compensating modules, (DCMs) or tunable dispersion compensator modules (TDCMs). The technology is also used in Proximion´s Optical Layer Monitor (OLM) product WISTOM™ and customized special products. |
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