Radially polarized mode-locked Nd:YAG oscillator

This paper demonstrates, that by exploiting the specific properties of the thermally induced refractive index changes in the laser active medium it is possible to modify the stability of a laser oscillator such that its preferred state of polarisation is radial. Later this scheme is extended towards Q-switched laser systems. With a carefully designed resonator which included a Nd:YAG crystal, a spherical lens, an aperture and an active electro-optic mode-locker, it was possible to show, for the first time, that is feasible to produce picosecond, radially polarized laser pulses, emitted directly from the oscillator and without any extra-cavity manipulations.