All optical clock recovery includes a transmitter for generating an optical timing signal. The transmitter includes a semiconductor laser for the production of a dynamically synchronizable timing signal, the laser having an external resonator for feedback of the timing signal to the laser, the feedback having a delay time greater than a relaxation oscillation time for the laser, and the laser outputting an optical timing signal having a characteristic dynamic. The transmitter supplies the optical timing signal to a receiver configured to receive the timing signal and to synchronize to the laser on receipt of the timing signal, such that the receiver outputs a recovered timing signal having the characteristic dynamic. A number of receivers may be provided in sequence along an optical path, each receiver configured to receive the timing signal originally outputted with the characteristic dynamic from the transmitter, and synchronized to the transmitter on receiving the signal and thereby outputting a recovered timing signal having the characteristic dynamic. All optical clock recovery is provided without increased electronic complexity and avoids thermal drift.