| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical transmitter that has a function of preventing in advance deterioration in the reception sensitivity due to a decreased luminous quantity. SOLUTION: The optical transmitter consists of a transmission section T where an optical modulator 3 modulates an output light of a semiconductor laser 1 with a transmission signal of a transmission signal source 2 and outputs a modulated laser beam and of a reception section R where a photo diode 4 of a receiver 7 converts a signal light transmitted through an optical fiber OF, a preamplifier 5 amplifies and outputs an AC signal component included in the modulated laser beam, a notice signal generator 8 detects a voltage V0 (signal light intensity) corresponding to the luminous quantity of the modulated laser beam received by the photo diode 4, a comparator 6 compares the voltage V0 with a reference voltage Vref and the generator 8 generates a notice signal when the detected voltage V0 is the reference voltage Vref or below. |
