Gain-coupled DFB LDs with high dynamic single-mode yield at 2.5-Gbit/s modulation

Gain-coupled (G-C) DFB laser diodes (LDs) have many advantages, such as single-mode operation in principle, a high side-mode-suppression ratio (SMSR), and immunity to externally reflected light.1,2 It has been shown that the G-C DFB lasers can offer higher single-mode yield than can index-coupled (I-C) DFB lasers at dc.3 In practical use, however, the dynamic single-mode property is important for optical communication systems. In this paper the dynamic behavior at 2.5-Gbit/s modulation of G-C DFB lasers and the yield of dynamic single-mode lasers have been investigated. It is experimentally confirmed that the yield of dynamic single-mode G-C DFB lasers is substantially improved over that of I-C DFB lasers.