| Abstract: | The spectrum characteristics of
two kinds of single longitudinal mode laser diodes whose structures are buried heterostructure
(BH) and transverse junction stripe (TJS) modulated directly by low frequency sinusoidal
current signal is systematically investigated. The modulation frequency is less than 100 kHz. It
is found that, under the low frequency modulation, when the modulation depth is over some
values, the spectrum of these laser diodes will become multi longitudinal modes. It is different
from the general idea. Besides, under the same operating conditions, for those laser diodes
which have greater sidemode suppression ratio (MSR), or when the modulation frequency is
increased, it must increase the modulation depth for getting multi longitudinal modes. The TJS
laser diodes are easier to appear sidemodes than BH laser diodes. |
