| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical modulation circuit which achieves optical coding modulation for transmitting information of one bit per one symbol using a one Mach-Zehnder modulator.SOLUTION: An optical modulation circuit comprises: one two-input and two-output Mach-Zehnder modulation unit that is driven according to a data signal; a one-input and two-output optical branch unit optically connected to one output of the Mach-Zehnder modulation unit; a feedback optical path optically connected to a first output port of the optical branch unit and a second input port of the Mach-Zehnder modulation unit, for feeding back an optical signal from the first output port to the second input port; and a combining unit for combining an optical signal from a second output port of the optical branch unit and an optical signal from the second output port of the Mach-Zehnder modulation unit. The delay time of an optical signal propagating on an optical path from the first input port of the Mach-Zehnder modulation unit via the first output port of the optical branch unit and the feedback optical path to the second input port of the Mach-Zehnder modulation unit is a natural number multiple of a symbol time of the data signal.SELECTED DRAWING: Figure 1 |
