Patent ID: 7187814

Claim:
An optical add/drop device for adding/dropping an optical signal having a predetermined wavelength to/from a wavelength multiplexed optical signal which flows from a network, comprising: a dropping unit for dropping an input wavelength multiplexed optical signal; a splitting unit for splitting an optical signal having a predetermined wavelength from a first optical signal dropped by said dropping unit; a rejecting unit, which is configured by an acousto-optic tunable filter, for selecting a through optical signal by applying a corresponding RF signal to the acousto-optic tunable filter, for rejecting an optical signal to be rejected by storing an RF signal applied to the acousto-optic tunable filter, and for rejecting an optical signal having a same wavelength as that of an optical signal to be added from a second optical signal dropped by said dropping unit; and an adding unit for adding an optical signal having a predetermined wavelength to the optical signal which passes through said rejecting unit; a transponder unit for generating the light to be added, wherein said transponder unit comprises: an opto-electric converting unit, to which an optical signal to be added is input, for converting the optical signal into an electric signal, a multi-wavelength light source, a selecting unit for selecting light having a necessary wavelength from light output from said multi-wavelength light source, and a modulating unit for modulating the selected multi-wavelength light with the electric signal obtained by said opt-electric converting unit.