GLASS SUBSTRATE AND ITS TWO-STAGE FORMING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a glass substrate and its two-stage forming method facilitating the manufacture of the glass substrate that is superior in the surface precision of a recessed part such as a V groove part and a counter-bored part and has a dovetail-shape recessed part which has been difficult to manufacture. SOLUTION: The glass substrate 3 has on its top surface the V groove 18 for arraying and arranging a coated optical fiber and the counter-bored part 19 for storing the optical fiber clad part 16 on the prolongation of the V groove part 18. The surface roughness of the inside flank of the counterboare part 19 is <=1μm Rmax or <=0.2μm Ra at least at the connection part 17 between the V groove part 18 and counterbore part 19.