Narrowband LPFG filter based on a pair of fiber deformers

Summary form only given. Long period fiber gratings (LPFG) are attractive fiber optic devices which have various applications such as gain flattening filters in fiber amplifiers, band rejection filters, mode converters, sensors, etc. The fabrication processes of photoinduced LPFG have been well-established but usually require expensive equipment. The periodic fiber bending technique, which was first demonstrated for mode conversion in a dual mode optical fiber, has been attempted as an alternative to a photoinduced LPFG. The advantageous feature of an LPFG using periodic fiber deformation is its extremely simple fabrication process and coupling strength independent properties of resonant wavelengths. In this paper, we propose a new type of narrowband fiber filter using two identical fiber deformers; connected in series.