| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical isolator having wavelength selectivity relating to an optical device usable as the optical isolator as well as an optical amplifier and system including the optical device. SOLUTION: This optical isolator comprises polarizers P1 and P2 which have transmission axes to determine the polarization axes of the polarized light rays respectively transmitted therethrough and a double refractive element BE and Faraday rotator FR which are disposed between these polarizers P1 and P2. The double refractive element BE is set in its thickness in such a manner that the element is a wavelength plate to a first wavelength and is a half wave plate to a second wavelength different from the first wavelength. The Faraday rotating angle is set atπ/4, the angle formed by the transmission axes of the polarizers P1 and P2 atπ/4 and the angle formed by the transmission axis of the polarizer P1 and the optical axis of the double refractive element BE atπ/4. |
