Patent ID: 7027742

Claim:
An optical single-sideband modulated wave generator, comprising: optical modulator means for amplitude modulating an optical carrier by an electric modulation signal to obtain an optical double-sideband modulated signal, and optical signal sideband suppressor means for suppressing either one of the sidebands of said optical double-sideband modulated signal to derive therefrom an optical single-sideband modulated signal; said optical modulator means, comprising: an optical carrier terminal for receiving said optical carrier; an electrical modulation signal terminal for receiving said electric modulation signal; optical amplitude modulator means for amplitude-modulating said optical carrier with said electric modulation signal to obtain said optical double-sideband modulated signal; a two-output waveguide optical branching unit for branching the input to or output from said optical amplitude modulator into first optical waveguide path and second optical waveguide path; and at least one optical-carrier phase shifter disposed in at least one of said first optical waveguide path and second optical waveguide path, for phase shifting said optical carrier by a required amount of phase shift; wherein first optical double-sideband modulated signal and second optical double-sideband modulated signal are obtained at the outputs of said first outputs of said first optical waveguide path and said second optical waveguide path; said optical signal sideband suppressor means, comprising: optical combiner means for combining said first optical double-sideband modulated signal and said second optical double-sideband modulated signal; wherein said required phase shift by said optical-carrier phase shifter is defined such that optical carrier signals of said first optical double-sideband modulated signal and said second optical double-sideband modulated signal have a relative phase difference of 90° when said first optical double-sideband modulated signal and said second optical double-sideband modulated signal are combined in said optical combiner means; wherein a baseband-signal-component 90° phase shifter is disposed in one of said first and second optical waveguide paths to obtain a 90° phase difference between a base band signal component of said optical double-sideband modulated signal on said one of said first optical waveguide path and said second optical waveguide path and a base band signal component in said optical double-sideband modulated signal on the other of said first optical waveguide path and said second optical waveguide path, when said first and second optical double-sideband modulated signals are combined in said optical combiner means; and wherein an optical delay circuit is disposed in the other of said first optical waveguide path and said second optical waveguide path to delay said optical double-sideband modulated signal on said other optical waveguide path by a predetermined time length in said baseband-signal-component 90° phase shifter.