HIGH-ISOLATION POLARIZATION-INDEPENDENT OPTICAL QUASI-CIRCULATOR WITHA SIMPLE STRUCTURE

A high-isolation polarization-independent optical quasi-circulator wit h a simple structure is proposed. A Porro prism is employed in this ki nd of device for what is believed to be the first time. Because a Porr o prism is used, light beams pass back and forth through the main elem ents in the device. Thus the number of elements used in the device is decreased, and the device structure is simplified. A four-port quasi-c irculator with monomode fibers was assembled and tested at the 1.55-mu m wavelength. Its insertion loss, isolation, and return loss are less than or equal to 1.63, greater than or equal to 60, and greater than or equal to 55.6 dB, respectively. (C) 1998 Optical Society of America .