A new configuration of an optical isolator chip, which is suitable for
use in integrated in-line optical isolators, has been proposed. The c
hip consists of a birefringent plate, a pair of birefringent wedges, a
nd a Faraday rotator. The configuration makes the best use of transmis
sion characteristics of expanded-core fibers in which the chip is embe
dded. The measured insertion Loss and isolation of an assembled isolat
or at the wavelength 1.55 mu m are 0.8- and 33-dB, respectively.