Ring Laser Gyroscope Operating at Exceptional Point with Extremely High Sensitivity

IFOS Corporation and Prof. Michel Digonnet at Stanford University propose an innovative ring laser gyroscope that utilizes emerging non-Hermitian photonics concepts and operates at an exceptional point (EP) to enhance its precision (angular random walk) by orders of magnitude. It consists of a small (~1-cm radius) ring resonator coupled upon itself by an asymmetric specialty grating that breaks the symmetry of the ringÆs two counter-propagating signals and enables the existence of an EP. The grating is the superposition of a conventional index grating and a gain grating fabricated as an InP overlay. The gratings are offset longitudinally from each other to introduce the required nonreciprocity in internal loss and reflectivity between counter-propagating signals. The performance of this EP ring laser gyro, in particular its sensitivity, noise, and temperature stability, will be investigated using coupled-mode theory, Hamiltonian operators, and commercial simulation tools. We will also design a read-out technique based on tracking of the measurable optical-spectrum splitting near the EP, induced by an applied rotation rate, which is expected to increase as the square root of the rotation rate. By implementing this concept in photonic integrated circuits, this significant improvement can be implemented while reducing size, weight, power, and cost.