| 摘要 |
PROBLEM TO BE SOLVED: To realize a FM modulator by which an intensity modulation component is sufficiently suppressed. SOLUTION: An electric signal (input signal) 13 is fed to a 180 deg. distributer 4, from which the signal is distributed into two, the signal whose phase is inverted by 180 degrees is given to a 2nd modulation light source 18, the signal whose phase is unchanged is given to a 1st modulation light source 17, where the signal is modulated by an optical signal with an intensity and an optical frequency depending on the amplitude of the signal. The two kinds of the optical signals are coupled by an optical coupler 25, the coupled signal is heterodyne- detected by a light receiving element 27. Since phases of the two kinds of the optical signals received by the light receiving element 27 differ by 180 deg., the optical intensity modulation components are added and cancelled out. The optical frequency components are multiplied with each other and the frequency deviation is doubled. |
