| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical comparator and a variable optical signal attenuator high in reliability whose cost is efficient, used for an optical signal processing system. SOLUTION: The device is equipped with an optical thresholding element 16 disposed along an optical path which has a prescribed threshold level and is regulated by the propagation direction of an optical input beam 12. When a light source generates the control beam 22 which passes the optical thresholding element and the comprehensive strength of the optical input beam and the control beam exceeds the threshold level of the thresholding element, the light beam passes the thresholding element. The thresholding element attenuates the light beam, when the light beam passes. The optical thresholding element, preferably, is a saturable absorber. When the device is composed as an optical comparator and the strength of the optical input beam exceeds the threshold level of the thresholding element, the thresholding element is saturated and becomes permeability, therefore the control beam passes the thresholding element as an optical indication beam, and the optical input beam also passes the thresholding element, and the thresholding element is not saturated with the comprehensive strength of the optical input signal and the control beam, when it is composed as an optical signal attenuator and the strength of an optical input signal can be ignored as compared with the control beam. |
