Systems and methods for reduction of optical signal linewidth

A method comprising:

• resonating an optical signal between a first end and a second end of an optical resonator cavity at a resonant frequency;
• passing a first portion of the optical signal through the first end into a first anti-resonator;
• and passing a second portion of the optical signal through the second end into a second anti-resonator, wherein the resonant frequency is within a stopband of the first anti-resonator and the second anti-resonator;
• wherein one or more phase modulation devices are attached to at least one of the optical resonator cavity, the first anti-resonator, and the second anti-resonator, wherein each phase modulation device in the one or more phase modulation devices respectively changes a length of at least one of the optical resonator cavity, the first anti-resonator, and the second anti-resonator;
• and reducing the length of the first anti-resonator and the second anti-resonator to increase the length of the optical resonator cavity while maintaining the resonant frequency of the optical resonator cavity within the stopband of the first anti-resonator and the second anti-resonator.

A system comprising:

• a laser that generates an optical signal;
• a resonator configured to receive the optical signal, wherein the resonator comprises:
• an optical resonator cavity comprising a first end and a second end, wherein the optical signal propagates in the optical resonator cavity at a resonant frequency;
• a first optical anti-resonator terminating the first end and having a first stopband including the resonant frequency;
• and
• a second optical anti-resonator terminating the second end and having a second stopband including the resonant frequency;
• a detector that generates an electrical signal from an output of the modified resonator;
• and
• Pound-Drever-Hall servo circuitry configured to generate control signals for controlling at least one of a frequency of the optical signal as generated by the laser and one or more phase modulation devices attached to at least one of the optical resonator cavity, the first optical anti-resonator, and the second optical anti-resonator, wherein each phase modulation device in the one or more phase modulation devices respectively changes a length of at least one of the optical resonator cavity, the first optical anti-resonator, and the second optical anti-resonator.