Optical component and optical apparatus comprising it

摘要

In an optical communication system using an optical fiber, it is forecasted that correct communication can not be ensured by a conventional wavelength dispersion compensation method due to increase in communication bit rate and communication distance and tertiary or higher-order wavelength dispersion compensation is required. But any effective countermeasure has been not proposed for tertiary wavelength dispersion compensation. A multilayer film (300) comprising at least four reflection layers (305, 304, 303, 302) having reflectance increasing sequentially from the incident side of signal light is employed as a tertiary wavelength dispersion compensation element in order to compensate for tertiary wavelength dispersion by generating a group velocity delay in the signal light. The thickness of the multilayer film as the optical path length is set equal to an integral multiple of a quarter of wavelength.