Patent ID: 6876810

Claim:
An optical attenuator comprising: a first optical component; a second optical component opposed to the first optical component across a space; a shutter plate for intercepting at least part of propagating light propagating from the first optical component to the second optical component; a first lens provided on a light-connecting end face of the first optical component; and a second lens provided on a light-connecting end face of the second optical component, a distance between the shutter plate and the second lens and a mode-field radius of the propagating light on a second-lens-side surface of the shutter plate being set so that respective signs of real and imaginary parts of an evaluation function, representing a diffraction pattern of the propagating light as a function of at least the distance and a coordinate value in a coordinate system set in the optical attenuator, are inverted a given number of times settled depending on required properties for the optical attenuator or more frequently when the coordinate value, serving as a variable of the evaluation function, is changed within an evaluation range defined according to at least the mode-field radius.