| 摘要 |
PROBLEM TO BE SOLVED: To obtain optimum characteristic for transmitting and receiving signals and to realize wide dynamic range at the receiving state by assembling a light source and a light modulator into a single module. SOLUTION: Using an optical element 21 that constitutes a laser resonator integrating a semiconductor light source 211 and a semiconductor light modulator 212 into single unit, applied voltage to the semiconductor light modulator 212 is controlled by the light modulator control circuit 23, injection current to the semiconductor light source 211 is controlled by a semiconductor light source control circuit 24 and the operating states of transmitting or receiving are switched by the control signal from a transmitting receiving control circuit 22. At the receiving state, the injected current to the semiconductor light source 211 is controlled to amplify the input light and the applied voltage to the semiconductor modulator 212 is controlled to increase photoabsorption index. At the transmitting state, the applied voltage is controlled to minimize the photoabsorption index of the semiconductor light modulator 212 and minimize the loss of it, and the injected current to the semiconductor light source part 211 is modulated by the transmitting signals to perform electric/optical conversion of transmitting signal. |
