Switching SBS gyro with fixed pump separation

A method comprising:

• generating, in an optical ring resonator and in response to a first pumped beam, a first back-scattered beam propagating in a direction;
• generating, in the optical ring resonator and in response to a second pumped beam, a second back-scattered beam propagating in an opposite direction;
• determining a first difference between the frequencies of the first and second back-scattered beams;
• reversing the directions of the first and second back-scattered beams;
• determining a second difference between the frequencies of the first and second back-scattered beams;
• determining a third difference between the first and second differences;
• and
• determining a rotation of the optical ring resonator in response to the third difference.

A system comprising:

• a navigation system comprising:
• one or more ring-laser gyroscopes, each of the one or more ring-laser gyroscopes comprising:
• a first optical pump configured to generate a first pumped beam;
• a second optical pump configured to generate a second pumped beam;
• an optical ring resonator configured
• to generate, in response to the first pumped beam, a first back-scattered pumped beam propagating in a direction opposite to a direction in which the first pumped beam is propagating, and
• to generate, in response to the second pumped beam, a second back-scattered pumped beam propagating in a direction opposite to a direction in which the second pumped beam is propagating;
• a switch having a first state in which the switch is configured to cause the first and second pumped beams to propagate in the optical ring resonator in first and second directions, respectively, and having a second state in which the switch is configured to cause the first and second pumped beams to propagate in the optical ring resonator in the second and first directions, respectively;
• and
• a detector coupled to the optical ring resonator and configured
• to determine a first optical beat signal in response to the first and second back-scattered pumped beams while the switch has the first state, and
• to determine a second optical beat signal in response to the first and second back-scattered pumped beams while the switch has the second state.