A photonic crystal interferometric optical gyroscope system including a
light source for providing a primary beam of light, a photonic crystal
sensing coil having a rotational axis, and a beam controlling device
configured to split the primary beam into first and second
counter-propagating beams in the photonic crystal sensing coil and
configured to direct return of the counter-propagating beams wherein the
power of the returning counter-propagating beams represents the phase
shift between the counter-propagating beams and is indicative of the rate
of rotation of the coil about the rotational axis.