DFB Laser Diodes for Analog Transmission

DFB laser diodes (LD) have been expected to be attractive light sources for analog transmission, because they have low noise characteristics in radio frequency. However, the early DFB-LD was difficult to apply to practical use because of their large modulation distortion. Main factors of the modulation distortion include 1) intrinsic nonlinear response, 2) spatial hole burning (SHB), and 3) leakage current. This paper reviews technologies of analog DFBLDs focused on the modulation distortion and a device structure to reduce them. CATV system is the most successful analog application for DFB-LDs. In addition, recent progress has been expanding new applications such as a microcellular radio communication. Here, the performance of DFB-LDs for those systems is shown. Furthermore, future trends of analog transmission and what the future analog application requires of DFB-LDs are also described.