OPTICAL CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide an optical circuit with the high-frequency characteristic improved by adjusting the characteristic impedance of a high-frequency transmission line.SOLUTION: An optical circuit includes: a semiconductor laser; an optical modulator that modules the optical output of the semiconductor laser in accordance with a modulation signal; an electric circuit that applies the modulation signal and the DC voltage from a DC power source to the optical modulator; an impedance line portion connected to the optical modulator and including a terminal resistor; and a control unit that monitors the value corresponding to a difference before and after the flow of current to a laser electrode from the DC power source when the DC voltage is applied, as a photocurrent flowing in the optical modulator, and changes the characteristic impedance of the impedance line portion including the terminal resistor in accordance with the monitor current.SELECTED DRAWING: Figure 17