Optical delay line and manufacturing method therefor

摘要

An optical delay line of a configuration in which a number of components such as a circulator and an optical coupler is reduced is to be provided. To this end, the optical delay line has a configuration in which, after an optical fiber (13) having a core subjected to refractive index modulation diffraction grating formation and a cladding partly cleared of its outer circumference and an optical fiber (14) having a cladding partly cleared of its outer circumference are brought close to each other so that the cores have mutually parallel directions of an optical axis to fabricate a directional coupler, both ends of the optical fiber (14) are connected into an optical fiber loop (16). In this way, an optical delay line to generate a specific time delay for controlling optical signals can be provided in small dimensions and with a small number of components. <IMAGE>