Study on the direct modulation characteristics of high power semiconductor laser

The direct modulation of high-power semiconductor laser driver that is composed of the current modulation circuit and the over-current protection circuit is introduced, two direct modulation circuits with different modulation output current amplitude are designed and the direct modulation of characteristics is analyzed, providing the output current waveform of the direct modulation of high-power semiconductor laser. In this paper, a new modulation output current with a peak current of 9.5A is designed with bias current of 0.8A and the modulation current bandwidth of 2.56MHz. The width of the modulation current pulse keeps stable after widening. When the input signal is voltage pulse with uniform pulse width, it can output current pulse with uniform pulse width. And the modulation output current with a peak current of 9.5A is designed with bias current of 0.8A and the modulation current bandwidth of 5MHz. We have a theoretical study on the dynamic characteristics of direct modulation of semiconductor laser. We also have done some experiments on the basis of the simulation, the experimental results show that the output pulse laser intensity and the pulse laser modulation signal width change with changing the width of the pulse, and the actual modulated output pulse laser has a certain time delay with respect to the modulated signal.