Wide Broadband ASE Source based on Thulium-doped Fibre for 2 μm Wavelength Region

This paper investigates the generation of the amplified spontaneous emission (ASE) from thulium-doped silica fibre pumped at 1570 nm. The developed model provides the ASE spectral power at short and long wavelength bands by using two different thulium doped fibre types with optimized fibre length. Shorter wavelengths in the emission band can be accessed with a short thulium fibre, whereas longer wavelengths can be obtained using a long thulium fibre. Our findings reveal that, in contrast to a 100 nm (1800nm-1900nm) and 70 nm (1900nm-1970nm) broadband source at short and long wavelength bands, a broader spectrum source can be achieved at about 170 nm (1800nm-1970nm) by a combined of the two ASE spectra via a wideband 50: 50 coupler. As a result, the proposed ASE source configuration doubles the bandwidth of the conventional single fibre based light source.