Optical Phase Interrogation

Avago Technologies has developed a unique, cost-effective sensor enabling technology utilizing a patented optical phase interrogation (OPI) technique. The technology enables multimode optical fiber to be used as a distributed sensor element for low-cost, light-weight industrial sensor designs, providing high electromagnetic interference (EMI) immunity and low electromagnetic susceptibility (EMS).

The technology enables readily available POF (Polymer Optical Fiber), PCS (Polymer Clad Silica), or MM ( Multimode) fiber to be used for creating robust high-precision strain sensors that rival other optical strain sensing technologies such as Fiber Bragg Gratings (FBG) and Optical Time Domain Reflectometry (OTDR). The technology has a broad range of applications in the structural health monitoring and industrial automation and control markets.

Avago OPI Highlights

  • Enables cost-efficient, mass producible optical fiber as a distributed sensor element
  • Easy handling and implementation of sensor electronics and fiber
  • Highly accurate, sensitive and scalable sensing solution
  • High EMI/EMC immunity for industrial sensor designs
  • Rugged interrogator transceiver electronics and fiber for system and gauge implementation

OPI Working Principle

The working principle is based on transmitting a fixed frequency, pulsed sinusoidal signal through two optical fibers and measuring the phase difference between the two optical output signals. One fiber is used as a sensing element on which strain is applied. The other fiber is used as an unstrained reference. The phase differential between the two optical output signals correlates to the relative strain between the two fibers. In effect, the phase differential is the amount of strain applied on a sensing element.