Abstract: A method and apparatus for generating optical pulses using an active mode-locking laser that includes a first modulation device, an optical selection device, a second modulation device and an amplification device. The method includes the steps of using the first modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a first direction, using the second modulation device to modulate a lightwave, selecting a modulation lightwave signal having a high frequency component by passing a lightwave through the optical selection device in a second direction, amplifying the lightwave selected by the above step, and supplying the amplified lightwave to the first modulation device.

Abstract: A method for transmitting high-frequency signals in an optical communication system includes combining an optical signal, the first optical local component from a local light source and the second optical local component from the local light source having a predetermined frequency differential from the first optical local component, selecting the first high-frequency signal which consists of two predetermined electrical components from plural electrical components obtained by the optical frequency mixing process, and mixing the two selected electrical components included in the first high-frequency signal.