The invention relates to an acoustic emission sensor (100). The acoustic emission sensor comprises an optical resonator (10) having a sensor region (11) configured for reflective operation; an optical waveguide (20) which is optically coupled to the optical resonator (10); a light source (31) which is optically coupled to the optical waveguide (20) to apply light to the optical waveguide (20); and a detection device (32) which is optically coupled to the optical waveguide (20) to detect light from the optical resonator (10). The sensor region (11) of the optical resonator (10) comprises a coupling device (50) for mechanically coupling to a solid measurement object (200). The coupling device (50) comprises a first coupling element (51) for transmitting an acoustic emission signal between the sensor region (11) and the solid measurement object (200), and at least one second coupling element (52). The second coupling element (52) is configured to position the coupling device (50) on the solid measurement object (200), and/or the second coupling element (52) acts as a filter for the acoustic emission signal.