A resonator fiber optic gyroscope, RFOG,, comprising: a master laser configured to emit a reference optical signal; a first slave laser configured to emit a first optical signal; a second slave laser configured to emit a second optical signal; an optical resonator ring cavity coupled to the master laser, first slave laser, and second slave laser, wherein the first optical signal propagates in a first direction through the optical resonator ring cavity, and the second optical signal propagates in a second direction through the optical resonator ring cavity; one or more signal generators configured to inject a first modulation signal at a first frequency and second modulation signal at a second frequency on both the first optical signal and the second optical signal; a first photodetector that generates a first signal corresponding to the first optical signal based on a signal exiting the optical resonator ring cavity at a first transmission port; a second photodetector that generates a second signal corresponding to the second optical signal based on a signal exiting the optical resonator ring cavity at a second transmission port; a first demodulator (130, 230, 330) configured to demodulate the first signal in phase with a first reference signal (131, 231, 331) and at the first frequency to produce a first demodulated signal; a second demodulator (132, 232, 332) configured to demodulate the second signal in phase with a second reference signal (133, 233, 333) and at the first frequency to produce a second demodulated signal, wherein the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) are derived from the first modulation signal; a differencing function configured to output the difference between resonance frequencies of the first signal and the second signal based on the first demodulated signal and the second demodulated signal; at least a third demodulator (144, 150, 246, 346) configured to detect a reference phase error of at least one of the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) using the second modulation signal; and at least one phase servo electronics module configured to adjust the phase of at least one of the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) based on the detected reference phase error. a master laser configured to emit a reference optical signal; a first slave laser configured to emit a first optical signal; a second slave laser configured to emit a second optical signal; an optical resonator ring cavity coupled to the master laser, first slave laser, and second slave laser, wherein the first optical signal propagates in a first direction through the optical resonator ring cavity, and the second optical signal propagates in a second direction through the optical resonator ring cavity; one or more signal generators configured to inject a first modulation signal at a first frequency and second modulation signal at a second frequency on both the first optical signal and the second optical signal; a first photodetector that generates a first signal corresponding to the first optical signal based on a signal exiting the optical resonator ring cavity at a first transmission port; a second photodetector that generates a second signal corresponding to the second optical signal based on a signal exiting the optical resonator ring cavity at a second transmission port; a first demodulator (130, 230, 330) configured to demodulate the first signal in phase with a first reference signal (131, 231, 331) and at the first frequency to produce a first demodulated signal; a second demodulator (132, 232, 332) configured to demodulate the second signal in phase with a second reference signal (133, 233, 333) and at the first frequency to produce a second demodulated signal, wherein the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) are derived from the first modulation signal; a differencing function configured to output the difference between resonance frequencies of the first signal and the second signal based on the first demodulated signal and the second demodulated signal; at least a third demodulator (144, 150, 246, 346) configured to detect a reference phase error of at least one of the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) using the second modulation signal; and at least one phase servo electronics module configured to adjust the phase of at least one of the first reference signal (131, 231, 331) and the second reference signal (133, 233, 333) based on the detected reference phase error.