Tuning characteristics of a long erbium doped fiber external cavity semiconductor laser for radio-over fibre applications

摘要

Measurements and analysis of electrical and temperature tuning characteristics of a 1490 nm erbium doped fiber external cavity semiconductor laser (DFECL) are presented. The laser has a long piece of doped fiber in the external cavity. The standing wave in the external cavity causes spatial hole-burning and absorption modulation in the saturable absorber, and forms a long dynamic grating. In this paper, we show that the wavelength of DFECL can be tuned within the bandwidth of the FBG (～100 pm), by tuning the semiconductor laser temperature. The wavelength of the laser can also be tuned smoothly and continuously over 60 pm by controlling the current over 160 mA; the equivalent optical frequency tuning rate is ～50MHz/mA. The results indicate that the peak wavelength of the dynamic grating can be tuned with the dominant mode within the bandwidth of the fiber Bragg grating. This fine tuning characteristic is very attractive for microwave optical generation in Radio over Fiber applications.