Highly stable polymethine-dye-based polymer switches for passive mode locking in neodymium lasers

Polymer passive laser switches were made from new polymethine dyes in a polyurethane matrix. They were designed for passive mode locking in neodymium lasers emitting 1.05–1.08 μm radiation. The service life of a local working zone of such a switch was found to be 10⁶ pulses with an energy of 4–6 mJ in a train. Pulse-periodic passive mode locking was achieved at frequencies 50–100 Hz. Replacement of polyurethane acrylate composites, formed by radical polymerisation, with polyurethane matrices, formed by the polycondensation method, increased by more than one order of magnitude the main operating characteristics of the lasers.