滝口由朗,劉雲
Experimental Observations of Dynamic Properties
in External Cavity Semiconductor Laser
with Multi-Mode Oscillation
Abstract:Laser diodes with optical feedback attract considerable attention both as a physical model
of nonlinear optical systems and from the application point of view. The stability and
instability of laser diodes with optical feedback oscillating in a single mode have been
widely investigated and various phenomena including chaos have been reported in single
mode models. [1-4] Besides the intensity fluctuations in the light output of the laser, the
external optical feedback also induces spectral instabilities including coherence collapse
and mode hopping. [5,6] A multimode model has been assumed when performing
feedback-induced noise control using high frequency injection current modulation in
compound cavity laser diodes. [7] Recently, a method for adaptive mode selection has
been proposed using the feedback-induced mode competitions among longitudinal modes
of a Fabry-Perot laser diode. [8,9] For both of the above applications, it is strongly
required that the feedback-induced dynamics of multimode laser diodes be experimentally
clarified.
The purpose of this report is to report the results of an experimental investigation
of mode hopping and high frequency modulation behavior of a compound cavity laser
diode with multi-modes. The compound cavity laser diode oscillates in single-, two-, or
multi-modes depending on the feedback and injection parameters. By analyzing the light
output of a particular longitudinal mode using a monochrometer, the mode hopping of the
compound cavity laser diode is observed and the mode dwelling time distribution is
investigated. The low frequency fluctuations (LFF) are also observed. Though the
LFF is usually observed in a compound cavity laser diode with single mode oscillation, it
is also observed here in a multimode case in our experiment. The LFF induced by a
high frequency modulation of injection current is also investigated.