Rapid, electronically controllable transverse mode selection in a multimode fiber laser.

A novel technique for the electronically-controllable generation and switching of transverse modes within a multi-mode fiber laser oscillator is presented. Preliminary results demonstrate individual transverse mode lasing and fast switching between modes with watt-level output powers. When applied to a core-pumped Tm-doped silica fiber laser with a multimode core the fundamental mode (LP₀₁), the next higher order mode (LP₁₁), or a donut-shaped LP₁₁ superposition were selectively excited with power levels in excess of 5 W. Fast switching between LP₀₁ and LP₁₁ modes at up to 20 kHz was also realized.