We present measurements and theoretical analysis of power partition fluctuations in a distributed feedback (DFB) laser operating CW with the two DFB degenerate modes as the only significant longitudinal modes. The power ratio of the two modes was varied from 1:1 to 2500:1 by electrical control using a novel two-electrode DFB laser. The laser was observed to exhibit 1) transient power dropouts and 2) two-mode relaxation oscillation. The dropout depths were less than 30 percent of the main-mode power in all cases, except when the laser was subjected to external optical feedback. The relaxation oscillations of the two mode powers are anticorrelated, which is different from the well-known relaxation oscillation of the total output power due to photon-carrier interaction. The calculated result based on a Fokker-Planck analysis agrees with the experiment, except for the two-mode relaxation oscillation, which was not considered in the theory.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics