OPTICAL DEVICE FOR TAKING-OUT MONITOR LIGHT

摘要

PROBLEM TO BE SOLVED: To provide an optical device for taking-out monitor light having no dispersion in individual optical characteristics and capable of yielding stable monitor light. SOLUTION: There is provided an optical device 10 which takes out, from output light 13, monitor light 13a for generating a control signal S inputted into a light source 11 in order to control output light 13 radiated from the light source 11 whose output is adjustable to an optical waveguide device 12 such as an optical fiber. The optical device 10 is composed of an optical board 15 which is inserted into an optical path from the light source 11 to the optical waveguide device 12 and has a branching function for branching part of output light 13 as monitor light 13a and a light condensing function for condensing output light 13 from the light source 11 onto the optical waveguide device 12. A CGH element 16 imparting the light condensing function to the board is formed on the optical board 15.