An embodiment of the invention relates to an optical device which is capable of realizing a secondary nonlinear optical phenomenon. The optical device is a fiber-type optical device which is comprised of glass containing SiO2, and includes a core region, a first cladding region, and a second cladding region. At least a part of a glass region configured by the core region and the first cladding region has such a repetition structure that a first section serving as a poled crystal region and a second section serving as an amorphous region are alternately disposed along a longitudinal direction of the optical device.