Theory of 'tunnel' mode locking in lasers

The possibility of a tunnel synchronization of modes in lasers with a dispersive medium in a resonator is discussed. This mode locking is a result of the tunnel-type passage of subpicosecond light pulses through a dispersive medium, when the latter has a characteristic tunneling length along the resonator axis. The theory of tunnel mode locking is developed for Kerr synchronizing nonlinearity. Equations are derived which describe the dynamics of the phase change of the generated modes. For the case of three generated modes, the locking band is determined, and the frequency modulation of the modes outside the locking band is predicted. An estimation of the locking band for an arbitrary number of generated modes is given; results show the possibility of generating light pulses with a duration of up to 3 x 10 to the -14th sec.