A fiber optic gyroscope comprising: an optical fiber coil; and at least one optical circuit in optical communication with the optical fiber coil and configured to be in optical communication with at least one optical source, the at least one optical circuit configured to receive input optical signals generated by the at least one optical source, to split each input optical signal into a first optical signal and a second optical signal, to phase modulate one or both of the first optical signal and the second optical signal using a square-wave biasing modulation waveform, to transmit the first optical signal and the second optical signal to the optical fiber coil such that the first and second optical signals counterpropagate through the optical fiber coil, to receive the first and second optical signals after counterpropagating through the optical fiber coil, to combine the first and second optical signals after counterpropagating through the optical fiber coil, and to transmit the combined first and second optical signals to at least one photodetector; characterized by further comprising: at least one optical gate configured to controllably time modulate the input optical signals and/or the first and second optical signals prior to being combined, wherein the at least one optical gate comprises an input port and an output port, said time modulating synchronized with said phase modulating such that, (i) during first periods when the square-wave biasing modulation waveform is changing from negative to positive and during second periods when the square-wave biasing modulation waveform is changing from positive to negative, a substantial fraction of optical signals received by the input port is blocked and/or re-routed from being transmitted to the output port; and (ii) at all other times, a substantial fraction of optical signals received by the input port is transmitted to the output port, wherein an optical power of the optical signals transmitted from the input port to the output port during the first and second periods is less than an optical power of the optical signals transmitted from the input port to the output port during all other times. an optical fiber coil; and at least one optical circuit in optical communication with the optical fiber coil and configured to be in optical communication with at least one optical source, the at least one optical circuit configured to receive input optical signals generated by the at least one optical source, to split each input optical signal into a first optical signal and a second optical signal, to phase modulate one or both of the first optical signal and the second optical signal using a square-wave biasing modulation waveform, to transmit the first optical signal and the second optical signal to the optical fiber coil such that the first and second optical signals counterpropagate through the optical fiber coil, to receive the first and second optical signals after counterpropagating through the optical fiber coil, to combine the first and second optical signals after counterpropagating through the optical fiber coil, and to transmit the combined first and second optical signals to at least one photodetector; (i) during first periods when the square-wave biasing modulation waveform is changing from negative to positive and during second periods when the square-wave biasing modulation waveform is changing from positive to negative, a substantial fraction of optical signals received by the input port is blocked and/or re-routed from being transmitted to the output port; and (ii) at all other times, a substantial fraction of optical signals received by the input port is transmitted to the output port, wherein an optical power of the optical signals transmitted from the input port to the output port during the first and second periods is less than an optical power of the optical signals transmitted from the input port to the output port during all other times.