Temperature dependence of signal gain in Er3+-doped optical fiber amplifiers

Temperature-dependent signal gain characteristics at signal wavelengths of 1.536 and 1.552 μm in Er³⁺-doped optical fibers with a temperature range of -40 to 80°C are reported for 0.98 and 1.48 μm pumping. The temperature dependences of signal gain strongly depend on fiber length, pump wavelength, and signal wavelength. The fiber length at which signal gain temperature insensitivity occurs is found for the amplification of a 0.98-μm-pump-1.536-μm-signal, a 0.98-μm-pump-1.552-μm-signal, and a 1.48-μm-pump-1.536-μm-signal. It is confirmed theoretically that the temperature dependences result from linear changes in the fluorescence, and absorption cross sections at the signal and pump wavelengths, and a shift in the effective pump wavelength