Overmodulation Gain Dynamics in Thulium Doped Fiber Amplifiers Including Amplified Spontaneous Emission

Erbium doped fiber amplifiers (EDFAs) gain modulation was extensively studied by Freeman and Conradi (1993), Novak and Moesle (2002), Sharma and Raghuvanshi (2017), however Thulium doped fiber amplifiers (TDFAs) provide high power optical amplification in S/S+ - band (1380 nm - 1550 nm, peak at 1490 nm) peering the C-band (1530 nm - 1560 nm) and L - band (1560 nm - 1580 nm) amplification based on EDFAs in dense wavelength division multiplexing systems (DWDM) in optical fiber communication. Bononi and Rusch (1998) presented the gain dynamics in EDFA however, extending this analysis in partial to TDFA haven't been studied till date as far as authors' study is concerned. Paper presents an extensive analytical model for gain modulation in TDFA, low frequency amplitude modulation (similar to 100 kHz) of a digital optical communication signal as a propagating system, for the surveillance and management of digital optical information in DWDM systems. Analytical expressions of transfer functions for signal-to-signal, signal-to-amplified spontaneous emission (ASE) showing system performance with respect to modulation index and signal frequency was developed.