Enhanced temperature sensitivity of fiber Bragg grating temperature sensor using thermal expansion of copper tube

The temperature sensitivity of fiber Bragg grating (FBG) temperature sensor is enhanced when using a copper tube to jacket of the FBG.Both sides of the FBG are glued with epoxy to cylindrical ferrules tubes that in turn is inserted and glued to a cylindrical copper tube. As the high thermal expansion coefficient of the cylindrical copper tube pulls both sides of the FBG, the temperature sensitivity is improved 3.3-fold when compared to that of a bare FBG. Copyright © 2011 Wiley Periodicals, Inc.

4 x 4 Plastic Optical Fiber Star Coupler Incorporated with a Common Polymer Waveguide Optical Power Distribution Region

Two types of 4×4 plastic optical fiber star couplers incorporated with a polymer waveguide as the optical power distributor are proposed, and their high performances are demonstrated. The characteristics of the proposed star coupler are investigated based on ray optics, and its power distribution performance is evaluated in terms of the flatness of the coupling ratio and the amount of the excess loss. Under the best conditions, the flatness of the coupling ratio and the excess loss of the fabricated device have been obtained as 2.0 dB and 2.5 dB, respectively. © 2011 Taylor & Francis Group, LLC.