Fiber optic grating-based weighted, two-mode fiber sensors

Publication Date
1993-05-04Filing Date
1991-08-29Inventor
Murphy, Kent A.
Claus, Richard O.
Vengsarkar, Ashish
Fogg, Brian R.
Greene, Jonathan A.
Metadata
Show full item recordAbstract
Two-mode, elliptical-core optic fibers with a permanent photo-induced index change are used as sensors with sensitivity varying as a function of length. The optic fiber sensors act as vibrational-mode filters thereby performing initial signal processing of the sensor signal. The sensors are based on photo-induced refractive index changes. These refractive index changes affect the differential phase modulation between the LP.sub.01 and the LP.sub.11.sup.even modes. The change in beat-length is dependent on the amount of strain induced in the fiber while the grating is being formed. The pattern is thus varied along the length of the fiber by straining the fiber in a specific fashion while the grating is being written. This changes the sensitivity, of the sensor along its length. By choosing an appropriate weighting function in the manufacture of the sensor, it is possible to implement vibrational-mode analysis, vibrational-mode filtering and other functions that are critical in control system applications.
Assignee
Center for Innovative Technology
VPI & SU
Patent Number
5208877
Application Number
7751737
Primary/U.S. Class
250/227.14
Other/U.S. Class
385/12
385/13
385/28
CPC Class
G01D5/3538
G02B6/02047
G02B6/02123
G02B6/14
Patent Type
utility
Collections
- Virginia Tech Patents [545]