| 摘要 |
PROBLEM TO BE SOLVED: To provide a modulation method and equipment which reduces interference noise. SOLUTION: A modulation method and equipment of laser diode in an optical fiber transmission system. The equipment is composed of an oscillator circuit 80 which lets generates a low frequency signal at a bias terminal 14 of a laser diode module 10, a level controller LPF 90 which controls the output level of the oscillator circuit 80. And a bias current from a bias circuit 20 and a low frequency signal which is output from the LPF 90 are superimposed and are applied to the bias terminal 14. Hereby, regardless of with or without of a high frequency signal of a signal input terminal 15, an applying voltage of the laser diode module 10 is continuously varied. In other words, the continuous oscillating optical spectrum width is widened according to the signal amplitude of the low frequency signal. As the spectrum width is widened the coherence decreases and the interference noise is reduced. |
