Fiber optic resonant ring sensor and source

A laser source comprising a laser diode having a lasing cavity with one end thereof tightly coupled into a resonant fiber optic ring such that the diode receives only Rayleigh backscattered light from the ring, in an amount effective to narrow the line width of light produced by the laser diode, forward propagating light in the ring constituting a line narrowed output of said laser source.

An improved fiber optic sensor, of the type wherein laser beams derived from a laser source are propagated in a fiber ring to develop signals indicative of a physical state sensed by the ring, and including feedback means operative on a said beam to maintain its resonant frequency in a resonant mode of the ring, wherein the improvement resides in that the fiber ring is a resonant ring formed as a coil having first and second essentially contiguous light conducting cores and said first core is coupled to a laser diode cavity to narrow the line width of the laser diode, the line width narrowed output of the laser diode being provided as an input to said second core, said laser beams being propagated in said second core to develop said signals.

An improved method of providing a coherent source of light, wherein the improvement comprises the steps of

• i) coupling a light output of a laser diode as a forward propagating beam along a path into a resonant fiber optic ring such that the laser diode receives only Rayleigh backscattered light along the path in an amount effective to narrow its line width, and
• ii) coupling a portion of said forward propagating beam as a light output thus constituting a line narrowed coherent source of light.

An improved method of performing high resolution sensing of an inertial parameter via a resonant fiber optic ring, wherein the improvement comprises forming said ring with first and second fiber cores in parallel along an essentially common contiguous winding path, circulating light in said first core to develop a reference laser source, and providing said reference laser source to said second core for sensing of the inertial parameter.

An improved method of sensing a parameter with a resonant fiber optic ring, wherein the improvement comprises coupling a laser diode to the ring to receive only Rayleigh backscattered light therefrom in an amount effective to narrow the line width of the laser diode thereby achieving a narrow line output, and applying said narrow line output to develop a sensing beam.