| 摘要 |
PROBLEM TO BE SOLVED: To make the grating small-sized by forming a grating part in a polarization plane maintaining fiber. SOLUTION: A PANDA fiber 10 consists of a core 11 made of quartz glass to which germanium is added, a clad 12 made of pure quartz glass, and a stress imposing part 13 made of quartz glass to which a relatively large amount of boron is added. At one place of the PANDA fiber 10 which is different in effective refractive index to an Xpolarized wave, the core 11 is given periodical variation in refractive index along the length of the PANDA filter 10 to constitute one kind of grating part. Consequently, different grating characteristics are shown to the X-polarized wave and Y-polarized wave of light transmitted through the grating part, and a transmission spectrum having two loss peaks is obtained, so that this grating can be used as a two-wavelength stop type optical fiber grating. |
