| 摘要 |
PURPOSE:To observe an oscillation spectrum in the transient state of a DFB laser and to accurately evaluate transmission characteristic by applying a current for generating only a first optical pulse of a relaxation oscillation to the laser. CONSTITUTION:A transmission characteristic measuring pulse pattern generator 22 applies a DC bias current for generating only a first optical pulse of a relaxation oscillation to a DFB laser 24 and an electric pulse to be superposed thereon through a terminal T1. Then, the generation of an FP mode is confirmed. Thereafter, a channel selector 30 is switched to an optical fiber 40b, and the oscillation spectrum of the laser 24 is observed. Since an improper component for deteriorating the transmission characteristic and a proper component have different oscillation spectra of the FP mode, the component is proper or not is judged based on the depth of the FP mode. |
