Alternating Linear Polarization State in a Neodymium-Doped Fiber Laser with Modulated Pump

we present an analysis for the alternating linear polarization (ALP) state in a multi-longitudinal-mode laser with external modulation, and propose a new method for detecting this state. In a neodymium-doped fiber laser with a modulated pump, the ALP state is experimentally observed at both periodic and chaotic oscillation.