Patent ID: 7389009
Filing Date: 2008-06-17
Classification: G01N

Abstract:
1. An optical fiber sensor comprising: an optical fiber portion for transmitting light; mode restriction releasing means including a light permeable member melt bonded to a front end of the optical fiber portion, guiding at least a portion of the light transmitted by the optical fiber portion to the outside of a core to release a restriction of the mode of the light, and returning the light released in the restriction of the mode into the core, said mode restriction releasing means being a hetero core provided with a light transmitting core having a different diameter from the core of the optical fiber portion and able to transmit light propagated through the core and shorter in comparison with the length of the optical fiber portion; and further comprising: a metal film provided at a surface side of said hetero core and generating surface plasmon by reflection of light in the hetero core at that surface; and reflection means for reflecting light in the hetero core and returning the light to said optical fiber portion side at the surface of the end of the hetero core opposite to the end melt bonded to the optical fiber portion.