Optimized hybrid Silica TDFA-RAMAN wideband amplifier yielding flat gain in S-Band

For S-Band wavelength division multiplexing (WDM) systems Silica based Thulium doped fiber amplifier (TDFA) is a main amplifying media. But the gain provided by TDFA alone is low and not flat in entire S-Band. In this paper, Raman amplifier in hybrid configuration with TDFA has been used to flatten the gain. The gain curves for the TDFA alone are analyzed and optimized for TDFA length and Thulium doping concentration then the overall gain of hybrid configuration is flattened by controlling the gain of Raman amplifier. It has been observed that fairly flat gain curve (5dB variation) in S-band region (1460 nm to 1500 nm) is achieved, maximum gain of 31.1dB at 1470nm and lowest gain of 26.1dB at 1500nm have been observed.