摘要 |
Disclosed is a temperature compensated long period optical fiber grating filter. The long period optical fiber grating filter includes a core formed with a long period grating, a cladding surrounding the core, a coating coated over a portion of the cladding not surrounding the long period grating, and a re-coating coated over a portion of the cladding surrounding the long period and made of a material exhibiting an increase in refractive index in accordance with an increase in temperature, the re-coating serving to allow a coupling wavelength shift caused by the increase in refractive index to be carried out in a direction opposite to that of a coupling wavelength shift caused by a refractive all index difference between the core and the cladding. In accordance with this long period optical fiber grating filter, a temperature compensation can be more easily achieved without any inconvenience caused by an adjustment of refractive index in the filter or an addition of a material for avoiding a variation in refractive index depending on temperature.
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