Ring laser employing unidirectional attenuator

摘要: A mode locked fiber ring laser comprising an optical fiber, output mirror, a partially reflective/partially transmissive mirror and unidirectional attenuator. The attenuator comprises, in sequence, first linear polarizer, with its polarization axes at 0°, quarter wave plate axis θ°, non-reciprocal rotator for rotating the of incident light by γ°, second accented (θ+γ+90)° polarizer γ°. parameters θ γ are selected to provide desired relative phase shift between counter-propagating beams attenuate beam one directions so as create additive pulse mode-locked (APM) type passive locking system.