Abstract: An optical fiber 4 having a clad diameter of 125 ?m is made by adding Ge to a core 41 having a core diameter of 8 ?m and a relative refractive index difference of 0.3 %, and two refractive index grating portions 41a and 41b having a slant angle of 2° are formed in series in the optical fiber 4 by a phase mask method using KrF excimer laser (?=248 nm). The central period (2?) of the phase mask of a chirped grating is 1,140 nm, the chip rate (C) of the period is 1.2 nm/mm, the length (G) of the first and second index grating portions 41a and 41b is 8 mm, the effective refractive index of the first and second index grating portions 41a and 41b is 1.447, the refractive index modulation is 3×10?3, and the gap between the first and second index grating portions 41a and 41b is 1 mm.

Abstract: An SC-type optical PAD connector (4) has a ferrule (6) for accommodating a certain length of an optical fiber (5) which comprises a core containing a light absorbing dopant such as Co or V for adjusting the intensity of the received signal within a permissible range and a photosensitive dopant such as Ge or Sn for selectively reflecting the input light and provided with a chirped grating, which is a periodic modulation structure for the refractive index, in the longitudinally middle portion and a cladding formed outside of the core and having a refractive index smaller than that of the core. The certain length of the optical fiber (5) is protected by the ferrule (6) and fitted in a housing (7) and the connector (4) has one end formed into a male connection terminal and the other end formed into a female connection terminal.