Unidirectional operation in a dual-configuration resonator with three Nd:YVO/sub 4/ rods

Summary form only given. The novel resonator features efficient totally polarised fundamental-mode output and unidirectional operation in a compact and scaleable architecture. The anisotropy of the laser crystals enforces unidirectional operation and completely avoids thermally induced depolarisation. The resonator architecture is shown and is an advanced version of the original variable-configuration resonator (VCR). We observed and explain that the original resonator supports unexpected modes with circular polarisation at the linear polariser. Due to this the output of the VCR with Nd:YAG rods was completely un-polarised. The improvement was now achieved by replacing the quarter-wave plates (QP) by Faraday rotators (FR) allowing for the use of birefringent crystals.