We proposed and experimentally demonstrated an all-fiber source of broadband (visible or near infrared) light with modulated spectrum pumped by a picosecond Nd:YAG laser (1064 or 532 nm). Spatial separation of areas for light generation and spectral filtering in such a device consisting of a section of twin-core fiber and a directional coupler constructed at its exit end, as well as rigid control of coupling parameters by employing splicing/tapering technique, allowed us to develop the broadband source of ultrashort light pulses with a specific spectral form.