Patent ID: 7986452

Claim:
A multiplied harmonic signal generating method by means of a first Mach-Zehnder modulator and a second Mach-Zehnder modulator, where the first and second Mach-Zehnder modulators are high extinction ratio type and connected in tandem, the method comprising: suppressing odd order components of output light by driving the first Mach-Zehnder modulator in a full bias mode; eliminating by using a first optical filter a 0th order component from the light to obtain; a 2nd order component and a −2nd order component from the filtered light, wherein the 2nd order component and the −2nd order component enter into the second Mach-Zehnder modulator; suppressing odd order components of output light by driving the second Mach-Zehnder modulator; filtering optical components that are not −4th order component and 4th order component; and obtaining an 8th harmonic wave component by obtaining a difference component between the 4th order component and the −4th order component from the filtered light, the frequency of the 8th harmonic wave component being 8 times of a frequency of a modulating signal.