NARROW LINEWIDTH BRILLOUIN LASER

• US 20130083813A1
• Filed: 11/27/2012
• Published: 04/04/2013
• Est. Priority Date: 12/08/2009
• Status: Abandoned Application

• Current Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Original Assignee: Schlumberger Technology Corporation (Schlumberger NV)
• Inventors: Hartog, Arthur H.
• Application Number:
  US13/686,567
• Publication Number:
  US 20130083813A1
• Time in Patent Office: Days
• US Class Current: 372/6
• CPC Class Codes: G01D 5/35335 Aspects of emitters or receivers used by an interferometer in an optical fibre sensor arrangement using multiple sensor devices using multiplexing techniques G01D5/35383
• CPC Class Codes: H01S 3/06791 Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/08031 Single-mode emission
• CPC Class Codes: H01S 3/094038 End pumping
• CPC Class Codes: H01S 3/1392 by using a passive reference, e.g. absorption cell H01S3/1396, H01S3/1398 take precedence
• CPC Class Codes: H01S 3/1398 by using a supplementary modulation of the output
• CPC Class Codes: H01S 3/302 in an optical fibre

Abstract

A Brillouin laser having a narrowed linewidth, reduced relative intensity noise, and increased output power includes a pump laser that provides pump energy to an optical fiber resonant cavity to stimulate Brillouin emission. The output of pump laser is stabilized and its linewidth is narrowed by locking the frequency and phase of the optical signal generated by the pump laser to a longitudinal mode of the optical fiber resonant cavity. In addition, the resonant cavity is temperature and/or strain-tuned so that the Brillouin gain is substantially centered on a longitudinal mode of the cavity, thereby ensuring that the Brillouin frequency shift is substantially equal to an integer number of the free spectral range of the cavity.

Claims

1. A method of providing a narrow linewidth optical signal comprising:

providing an optical source to launch a frequency-stabilized optical signal at a first frequency into an optical fiber resonant cavity, wherein the first frequency corresponds to a longitudinal mode of the optical fiber resonant cavity;

pumping the optical fiber resonant cavity to stimulate a Brillouin emission;

controlling a Brillouin frequency shift of the optical fiber resonant cavity so that a gain of the Brillouin emission is substantially centered on a longitudinal mode of the optical fiber resonant cavity;

outputting a narrow linewidth optical signal at a first-order Stokes wavelength of the Brillouin emission; and

inducing a narrowband loss in the resonant cavity to suppress a second-order Stokes wavelength of the Brillouin emission.

2. The method as recited in claim 1, wherein a free spectral range of the optical fiber resonant cavity is at least the same value as the bandwidth of the gain of the Brillouin emission.

3. The method as recited in claim 1, wherein controlling the Brillouin frequency shift comprises straining at least a portion of the optical fiber forming the optical fiber resonant cavity.

4. The method as recited in claim 1, wherein controlling the Brillouin frequency shift comprises adjusting a temperature of the optical fiber resonant cavity.

5. A narrow linewidth optical source, comprising:

an optical fiber resonant cavity to produce a Brillouin emission in response to receipt of optical power;

an optical source to launch an optical signal at a first frequency into the optical fiber resonant cavity;

a frequency stabilization circuit to lock the first frequency to a longitudinal mode of the optical fiber resonant cavity; and

an output to provide a narrow linewidth optical signal at a first-order Stokes wavelength of the Brillouin emission; and

a narrowband loss device to suppress a second-order Stokes wavelength of the Brillouin emission within the optical fiber resonant cavity,

wherein a Brillouin frequency shift of the optical fiber resonant cavity is stabilized so that a gain of the Brillouin emission is substantially centered on a longitudinal mode of the optical fiber resonant cavity.

6. The narrow linewidth optical source as recited in claim 5, wherein the launched optical signal at the first frequency provides the optical power to stimulate the Brillouin emission.

7. The narrow linewidth optical source as recited in claim 5, further comprising a thermal element to adjust a temperature of the optical fiber resonant cavity to stabilize the Brillouin frequency shift.

8. The narrow linewidth optical source as recited in claim 5, further comprising a strain element to impart a strain on at least a portion of the optical fiber forming the optical fiber resonant cavity to stabilize the Brillouin frequency shift.

9. The narrow linewidth optical source as recited in claim 5, wherein the optical fiber resonator cavity comprises a polarization-maintaining optical fiber.