Nonlinear interferometer systems and methods
Nonlinear interferometers include a nonlinear optical medium that is situated to produce a conjugate optical beam in response to a pump beam and a probe beam. The pump, probe, and conjugate beams propagate displaced from each other along a common optical path. One of the beams is selectively phase shifted, and the beams are then returned to the nonlinear medium, with the selectively phase shift beam phase shifted again. The nonlinear medium provides phase sensitive gain to at least one of the probe or conjugate beams, and the amplified beam is detected to provide an estimate of the phase shift.
1. A nonlinear interferometer, comprising:
a first beam source that produces a first beam at a first frequency;
a second beam source that produces a second beam at a second frequency;
an optical nonlinear medium that receives the first beam and the second beam, and produces a third beam at a third frequency in response to the first beam and the second beam;
a reflector situated to receive the first beam, the second beam, and the third beam from the optical nonlinear medium and return the first beam, the second beam, and the third beam to the optical nonlinear medium so as to provide a phase-dependent amplification to one or more of the first, second, or third beams; and
a phase modulator situated to receive at least one of the first, second, and third beams from the optical nonlinear medium, phase modulate the received beam, direct the phase-modulated beam to the reflector, receive the phase modulated beam from the reflector, and phase modulate the received phased modulated beam.
2. The nonlinear interferometer of claim 1 , wherein the nonlinear medium is a rubidium vapor cell.
3. The nonlinear interferometer of claim 2 , further comprising a focusing element situated to focus the first beam and the second beam so as to overlap in the nonlinear medium, wherein the first beam and the second beam propagate along parallel, displaced axes to the focusing element.
4. The nonlinear interferometer of claim 3 , wherein the focusing element is a lens.
5. A nonlinear interferometer, comprising:
a first beam source that produces a first beam at a first frequency;
a second beam source that produces a second beam at a second frequency;
an optical nonlinear medium that receives the first beam and the second beam, and produces a third beam at a third frequency in response to the first beam and the second beam; and
a reflector situated to receive the first beam, the second beam, and the third beam from the optical nonlinear medium and return the first beam, the second beam, and the third beam to the optical nonlinear medium so as to provide a phase-dependent amplification to one or more of the first, second, or third beams, wherein the reflector includes at least a first reflective surface and a second reflective surface situated to reflect at least one of the first beam, second beam, and the third beam so that the reflected beam is returned to the nonlinear element along a return axis that is displaced from an axis of incidence to the reflector.
6. The nonlinear interferometer of claim 5 , wherein the reflector is a right-angle prism or a corner cube.
7. The nonlinear interferometer of claim 1 , wherein the second beam is produced by frequency shifting a portion of the first beam.
8. The nonlinear interferometer of claim 1 , further comprising a first fiber coupler situated to receive the first beam and the second beam and couple the first beam and the second beam into the nonlinear medium.
9. The nonlinear interferometer of claim 8 , further comprising a second fiber coupler situated to receive the first beam, the second beam, and the third beam and direct at least one of the beams to the phase modulator.
10. The nonlinear interferometer of claim 9 , wherein the second fiber coupler is situated to receive the phase-modulated beam from the phase modulator and direct the phase modulated beam to the optical nonlinear medium.
11. The nonlinear interferometer of claim 10 , wherein the optical nonlinear medium is a highly nonlinear optical fiber.
12. The nonlinear interferometer of claim 1 , further comprising a photodetector situated to receive the amplified third beam.
13. The nonlinear interferometer of claim 1 , wherein the first beam is a pump beam and the second beam is a probe beam having a power less than that of the pump beam, and the probe beam is directed to the phase modulator.
14. The nonlinear interferometer of claim 1 , further comprising a photodetector situated to receive at least a portion of the third beam so as to detect the phase modulation applied by the phase modulator.
15. The nonlinear interferometer of claim 1 , further comprising a first fiber wavelength multiplexer situated to receive the first beam and the second beam and couple the first beam and the second beam into the nonlinear medium.
16. The nonlinear interferometer of claim 15 , further comprising a second fiber wavelength multiplexer situated to receive the first beam, the second beam, and the third beam and direct at least one of the beams to the phase modulator.
17. The nonlinear interferometer of claim 16 , wherein the second fiber wavelength multiplexer is situated to receive the phase-modulated beam from the phase modulator and direct the phase modulated beam to the optical nonlinear medium.
18. The nonlinear interferometer of claim 17 , wherein the optical nonlinear medium is a highly nonlinear optical fiber.
19. A method, comprising:
directing first and second optical beams into a nonlinear medium to produce a third optical beam;
directing the first, second, and third optical beams along a common optical path;
phase modulating one of the second optical beam and third optical beam along the common optical path;
directing the phase modulated beam and the remaining beams along the common optical path into the nonlinear medium to apply a phase sensitive amplification to at least one of the second optical beam and the third optical beam; and
detecting the amplified beam to determine the phase modulation.
20. The method of claim 19 , wherein the first and second optical beams produce the third optical beam by four wave mixing or three wave mixing.
21. The method of claim 19 , wherein the nonlinear medium is a single mode optical fiber.
22. A nonlinear interferometer, comprising:
a first beam source that produces a first beam at a first frequency;
an optical nonlinear medium that receives the first beam and produces a second beam at a second frequency and a third beam at a third frequency in response to the first beam; and
a reflector situated to receive the first beam, the second beam, and the third beam from the optical nonlinear medium and return the first beam, the second beam, and the third beam to the optical nonlinear medium so as to provide a phase-dependent amplification to one or more of the first beam, the second beam, or the third beam.
23. The nonlinear interferometer of claim 22 , further comprising a phase modulator situated to receive one of the first, second, and third beams from the optical nonlinear medium, phase modulate the received beam, and direct the phase-modulated beam to the reflector.
24. The nonlinear interferometer of claim 23 , wherein the phase modulator is situated to receive the phase modulated beam from the reflector and phase modulate the phase modulated beam.
25. The nonlinear interferometer of claim 24 , wherein the reflector includes at least a first reflective surface and a second reflective surface situated to reflect at least one of the first beam, second beam, and the third beam so that the reflected beam is returned to the nonlinear element along a return axis that is displaced from an axis of incidence to the reflector.
26. The nonlinear interferometer of claim 25 , wherein the reflector is a right-angle prism or a corner cube.
27. The nonlinear interferometer of claim 22 , wherein the second beam is produced by frequency shifting a portion of the first beam.
28. The nonlinear interferometer of claim 22 , further comprising a first fiber coupler situated to receive the first beam and couple the first beam into the nonlinear medium.
29. The nonlinear interferometer of claim 28 , further comprising a second fiber coupler situated to receive the first beam, the second beam, and the third beam and direct at least one of the beams to a phase modulator.
30. The nonlinear interferometer of claim 22 , wherein the optical nonlinear medium is a highly nonlinear optical fiber.
31. The nonlinear interferometer of claim 22 , further comprising a photodetector situated to receive the amplified third beam.
32. The nonlinear interferometer of claim 22 , further comprising a first fiber wavelength multiplexer situated to receive the first beam and couple the first beam into the nonlinear medium.
33. The nonlinear interferometer of claim 32 , further comprising a second fiber wavelength multiplexer situated to receive the first beam, the second beam, and the third beam and direct at least one of the beams to a phase modulator.
34. The nonlinear interferometer of claim 33 , wherein the second fiber wavelength multiplexer is situated to receive the phase-modulated beam from the phase modulator and direct the phase modulated beam to the optical nonlinear medium.
35. The nonlinear interferometer of claim 5 , wherein the nonlinear medium is a rubidium vapor cell.