Temperature dependence of Yb-doped superfluorescent fiber source

2-kW-level superfluorescent fiber source with flexible wavelength and linewidth tunable characteristics

“…And due to the gain competition, a variation in the central wavelengths has been observed [31][32][33], as presented in Fig. 2(b).…”

“…While the central wavelength at the long-wavelength side keeps almost unchanged compared with the pre-amplifier. By optimizing the operating temperature and the system parameters such as fiber length in the seed and amplifiers [31,32,35], it's possible to further suppress the ASE light, reduce the wavelength variation and increase the wavelength tunable range.…”

“…The intensity difference between the signal peak and the ASE background is approximately 35 dB. In addition, due to the gain competition, a variation in the central wavelengths has been observed [31][32][33] , as presented in Figure 2(b). The wavelength difference λ is defined as λ amp -λ seed , where λ amp and λ seed represent the central wavelengths of pre-amplifier 2 and the filtered seed, respectively.…”

“…The wavelength variation is related to the spectral distribution of the gain coefficient, and the central wavelength will drift towards the region with the maximum gain coefficient. The gain distribution in the spectral domain is dependent on the pump power, fiber parameters and even temperature [31,32] . In our case, the wavelength region with the maximum gain coefficient is located near 1070 nm (according to the ASE background), and thus the spectrum at 1068 nm shows a wavelength red-shift, whereas the central wavelengths over 1070-1085 nm have a small blue-shift and the spectra at 1090 and 1092 nm exhibit a larger blue-shift.…”

“…The redshift increases at the short-wavelength side, for example, the spectrum at 1068 nm shows a wavelength red-shift of approximately 0.6 nm after the main amplifier, whereas the central wavelength at the long-wavelength side remains almost unchanged compared with the pre-amplifier. By optimizing the operating temperature and the system parameters, such as fiber length, in the seed and amplifiers [31,32,35] , it is possible to further suppress the ASE light, reduce the wavelength variation and increase the wavelength tunable range.…”