FIBER BRAGG GRATING HAVING OFFSET EQUIVALENT MIRROR SURFACE AND ITS MANUFACTURE

摘要

PROBLEM TO BE SOLVED: To obtain a grating which has a narrow reflection factor spectrum distant from a 2nd lobe and reduced equivalent length. SOLUTION: A grating 10 formed in the core of an optical fiber 1 has a modulation profile, which is uneven and asymmetrical in refractive index along the length and the profile is represented with a curve which gradually and monotonously increases from a minimum value which is substantially zero to a maximum value. Here, the minimum value has a substantially horizontal tangent and corresponds to the end of the grating 10 and the maximum value also has a substantially horizontal tangent and corresponds to the other end of the grating 10.