Patent ID: 6559990
Filing Date: 2003-05-06
Classification: H04J,H04Q

Abstract:
An optical delay circuit for successively introducing delay times that are respectively equal to multiples of a unit time between parts of an input optical signal and an output optical signal, comprising:a first optical multiplexer having a first input port successively supplied with said parts of said input optical signal representative of pieces of data information at a predetermined wavelength and a second input port successively supplied with intermediate optical signals each representative of none of or at least one of said pieces of data information at another wavelength different from said predetermined wavelength in synchronism with said parts of said input optical signal and an output port for outputting a multiplexed optical signal representative of the piece of data information of one of said parts of said input optical signal at said predetermined wavelength and said at least one of said pieces of data information at said another wavelength; an optical demultiplexer having an input port connected to said output port of said first optical multiplexer and plural output ports, for outputting plural demultiplexed optical signals representative of said one of said pieces of data information at said predetermined wavelength and said at least one of said pieces of data information at said another wavelength; a first wavelength converter having input ports respectively connected to said output ports of said optical demultiplexer, for converting said plural demultiplexed optical signals to converted optical signals at said another wavelength and yet another wavelength different from said predetermined wavelength and said another wavelength; an optical switching unit having input ports respectively connected to output ports of said first wavelength converter, and having first output ports and second output ports connectable to said input ports, and being responsive to an instruction so as to selectively connect said input ports to said first output ports and said second output ports; a second wavelength converter having input ports selectively connected to said first output ports of said optical switching unit and having an input connected to one of said output ports of said first wavelength converter, and converting said converted optical signals to restored optical signals respectively representative of said pieces of data information at said predetermined wavelength; a second optical multiplexer having input ports respectively connected to said second output ports of said optical switching unit, and successively producing said intermediate optical signals from converted optical signals selectively supplied from said second output ports of said optical switching unit; a third optical multiplexer having input ports respectively connected to output ports of said second wavelength converter, and producing said parts of said output optical signal from said restored optical signals; a waveguide connected between an output port of said second optical multiplexer and said second input port of said first optical multiplexer, and introducing a delay time approximately equal to said unit time into the propagation of each of said intermediate optical signals from said second optical multiplexer to said first optical multiplexer; and a controller storing pieces of control data information representative of said delay times, and checking said pieces of control data information to control an optical loop consisting of said first optical multiplexer, said optical demultiplexer, said first wavelength converter, said optical switching unit, said second optical multiplexer and said waveguide to delay said pieces of data information by said delay times, respectively, by instructing said optical switching unit to selectively change respective optical connections from said first output ports to said second output ports.