Abstract: A signal cut-off device 4 includes an optical fiber which has a clad 42 on the outer periphery of a core 41, and first and second variation sections of a refractive index, 41a and 41b in which the period of a grating varies gradually along an optical axis are serially formed in the longitudinal direction of the core 41. An optical connector which is detachably connected to the predetermined place of an optical transmission line includes a housing which has a plug-styled portion at a front end part and a jack-styled portion at a rear end part, and a ferrule which is mounted in the plug-styled portion. The signal cut-off device 4 is installed in the hole of the ferrule. An optical fiber coupler includes a coupler body which multiplexes/demultiplexes an uplink signal (1260-1360 nm) and a downlink signal (1480-1580 nm), a COM port which is provided on the input side of the coupler body, and a 1.55 port and a 1.3 port which are provided on the output side of the coupler body.

Abstract: An optical waveguide device 1 having optical fiber arrays 3a and 3b and a waveguide chip 2 connected to each other. Insertion holes 6a and 6b are provided for optical fiber holding members 5a and 5b comprising quartz glass or the like. Optical fiber cores of the optical fiber arrays 3a and 3b are inserted into the insertion holes 6a and 6b and are fixed with an adhesive material. Parts of covering optical fibers 4a and 4b are also fixed to apertures of the optical fiber holding members 5a and 5b with the adhesive material. According to the present invention, the optical fiber cores do not move inside the optical fiber arrays 3a and 3b in high-temperature or high-humidity environments. Accordingly, the use of the optical fiber arrays combined with the waveguide chip 2 provides a highly reliable optical waveguide device excellent in mechanical characteristics and transmission characteristics.