Sub-picostrain sensing by laser frequency locking to a passive fiber Bragg resonator

We demonstrate, for the first time, a sensing architecture capable of detecting broadband dynamic strain beyond picostrain resolution, with signal frequencies extending from 100 Hz to beyond 100 kHz. The system uses a pre-stabilized external cavity diode laser to interrogate a passive fiber Bragg resonator, using the Pound-Drever-Hall frequency locking technique. The low-loss resonator comprises of a Bragg grating pair written in standard SMF-28 fiber.