Temperature-dependent study on L-band EDFA characteristics pumped at 980nm and 1480nm in phosphorus and aluminum-rich erbium-doped silica fibers

In this paper, we present a comparative study on temperature-dependent spectroscopic characteristics and L-band amplifier performance for aluminum-rich erbium-doped fiber (EDF) and in-house fabricated phosphorus co-doped EDF. Different pumping configurations were studied to conclude that the pump wavelength of 980nm with unequal forward/backward pump powers exhibited better temperature stability. Phosphorus EDF provided 19.41.4dB gain and 4.60.2dB noise figure (NF) from 1575-1615nm at room temperature (RT), for a multi-channel input signal of -25dBm in each channel, whereas the aluminum-rich EDF provided 20.35.1dB gain and 5.30.8dB NF. Using a single-channel input signal of -25dBm at 1625nm, phosphorus EDF maintained >10dB gain with a 9.6dB and 12dB gain increment than aluminum-rich EDF at RT and -60oC, respectively. The temperature-dependent gain (TDG) coefficient from 1575-1615nm was in the range -0.006 to -0.044 dB/oC for phosphorus EDF and 0.011 to -0.023 dB/oC for aluminum-rich EDF, over the temperature range -60 to +80oC. We propose a hybrid L-band amplifier concatenating aluminum-rich EDF with phosphorus EDF, to suppress the temperature dependence of phosphorus EDF and improve the gain bandwidth restriction of aluminum-rich EDF. The hybrid EDF exhibited multi-channel 20.93.9dB gain and 3.70.6dB NF from 1575-1615nm at RT. The TDG coefficient of the hybrid EDF remained almost constant from 1585-1615nm, contributing to a temperature-insensitive gain flatness