| 摘要 |
PURPOSE:To obtain a high signal versus noise characteristic by providing a band pass frequency filter filtering an output light from an injection synchronization laser and an optical detector detecting directly an output light from the frequency filter to the equipment. CONSTITUTION:A light source 4 for an optical transmitter 1 is realized by employing a laser oscillated at a single frequency such as a distributed feedback semiconductor laser, a distributed black reflection type semiconductor laser, a semiconductor laser with an external resonator and a gas laser or the like. An optical modulator 5 is driven by a transmission signal 6. In the case of obtaining a signal light subject to on/off keying modulation, an amplitude modulator 5 is required. In this case, the amplitude modulator 5 applies OOK (On/Off Keying) modulation by a coherent component to a coherent light outputted from the light source 4. Furthermore, a frequency filter 9 is realized by an interference filter. Then a signal light outputted from the frequency filter 9 becomes an output of an optical injection synchronization device 7. |
