Various optical fiber connectors using a graded-index fiber have been fabricated and good performances have been obtained during field trial tests. The average connection loss of a

-type, plug-in type, and

-link connector has been found to be 0.4, 0.34, and 0.62 dB, respectively. A new field assembly (FA) type connector using a precision made ceramic capillary has also been developed. This FA type connector is fabricated for use with single-mode fibers, and has a connection loss of 0.56 and 0.52 dB at 0.85 and 1.3 μm, respectively. By using coupling experiments between laser diodes and single-mode fibers, a laser module with a coupling loss of 1.8 dB under optimum alignment conditions has been fabricated.