OPTICAL AXIS ALIGNMENT METHOD FOR OPTICAL ELEMENT-PLANE OPTICAL WAVE CIRCUIT-OPTICAL FIBER UTILIZING PASSIVE ALIGNMENT METHOD

PROBLEM TO BE SOLVED: To provide an easy method for passive alignment of optical elements by alignment marks. SOLUTION: The remaining portions excluding the V-groove forming regions of a silicon substrate 90 are etched to a specified thickness. A planatarized mask material film 98 is formed on the silicon substrate 90. Mask patterns for etching the V-grooves are formed by etching back the mask material film 98 in such a manner that the silicon substrate 90 is exposed. The silicon substrate 90 exposed to the extent of exposing the side walls of the mask patterns is etched. The silicon substrate 90 exposing the mask patterns by etching barriers is subjected to wet process etching, by which the V-groove are formed.