The optical device where reflected grating was formed low and it is low production method null of reflected

摘要

PROBLEM TO BE SOLVED: To obtain a low reflection grating which have rectangular spectral characteristics by varying the core width of the waveguide and forming specific grating structure. ;SOLUTION: The grating structure is so constituted that the core width of the waveguide varies with the position Z of the waveguide in the propagation direction of light according to W=W₀-▵W.|sin(C.Z)|/|C.Z [where W₀ is the core width (core width on both sides) of the original waveguide), ▵W is the decrease width (difference between W₀ and core minimum width) of the core width, and C is an arbitrary constant], the envelope shape of a periodic uneven refractive index distribution varies according to a function |sin(C.Z)|/|C.Z|, and the phase of light of specific wavelength propagated in the waveguide shifts by π according to Z=mπ/C (m=..., -3, -2, -1, 1, 2, 3,...). Consequently, the low reflection grating which has the rectangular spectral characteristics is obtained.;COPYRIGHT: (C)1997,JPO