Design of a widely tunable fiber laser for broadband applications

The fiber optic communication networks are widely deployed to enhance the data carrying capacity of dense wavelength division multiplexing systems (DWDM). Nevertheless, the channel capacity in the DWDM systems is confined only to C-band (1530-1565 nm). This is due to the limited gain bandwidth provided by the conventional erbium doped fiber amplifier (EDFA). Therefore, L-band (1570-1610 nm) EDFA are required to enlarge the transmission bandwidth. Recently, ultra-wide band EDFA has been demonstrated which can provide flat gain in both C and L band. To test such broadband devices of DWDM system, broadly tunable light sources are required. The requirement for these tunable lasers is very stringent. They should provide high output power, large tuning range and unpolarized light to neglect polarization dependent loss or gain. One big advantage offered by the fiber lasers is its compatibility with universal telecommunication fiber and produce low intensity noise. Commercially, a huge quantity of lasers with different lasing wavelengths are used as a backup for transmitters DWDM networks. A spare laser is kept for each channel for secure communication. This approach is not very due to huge cost and large inventory volume. Widely tunable fiber laser can reduce the system cost and inventory significantly. In this proposal, we propose to develop a widely tunable fiber ring laser that could cover both C+L bands in the telecommunication window. To achieve broad tuning range, length optimization of the doped fiber, which acts as a gain media is needed. We will also investigate the length optimization technique in this proposed study. Other parameters e,g pumping wavelength, pumping configuration and its effects on the tuning range will be explored.