Techniques for reducing the bias error present in optical gyroscopes is disclosed. Such techniques include at least one path length adjustment member placed in an optical gyroscope resonator, which are configured to modulate the optical path length of the resonator so that bias errors attributable to the optical path length are shifted outside of the bandwidth of the optical gyroscope. In some embodiments, the at least one path length adjustment member includes a plurality of microheaters coupled to the resonator, in which case optical path length modulation is achieved by heating the resonator via the microheaters. Alternatively, a plurality of piezo-electric regions can be placed in the resonator, which enables optical path length modulation through electric field gradients applied to the piezo-electric regions.