Patent ID: 8693512

Claim:
An optical frequency referencing device, comprising: an optical waveguide having material properties conducive for Brillouin scattering; a tunable laser for launching first light of a tunable frequency into the optical waveguide for propagating therein in a first direction; a reference laser for launching second light of a reference frequency into the optical waveguide in a second direction for counter-propagating therein with the first light and for interacting with the first light by means of stimulated Brillouin scattering (SBS); one or more detectors coupled to the optical waveguide at at least one end thereof for detecting at least one of the first and second light after propagation thereof through the waveguide and for producing at least one electrical signal responsive to changes in optical power thereof; and, a frequency referencing controller (FRC) coupled to the first laser and the one or more detectors and comprising: a tunable laser controller operable to sweep the tunable frequency about the reference frequency in a frequency range exceeding two Brillouin frequency shifts Δν B in the optical waveguide; and, a signal analyzer configured for analyzing the one or more electrical signals produced during said sweeping and for determining a first value of the tunable frequency at which the first light experiences an SBS induced gain in the optical waveguide, and a second value of the tunable frequency at which the first light experiences an SBS induced loss in the optical waveguide, the first and second values providing a relative frequency reference for the tunable laser.