Ultra-Broadband Bismuth-Doped Fiber Amplifier Covering a 115-nm Bandwidth in the O and E Bands

In this article, we experimentally demonstrate an all-fiber optical amplifier using Bi-doped phosphosilicate fiber (BPSF) operating in both the O-band and the E-band, providing >20 dB gain from 1345 to 1460 nm for an input signal power of −23 dBm. A maximum gain of 31 dB with a noise figure (NF) of 4.8 dB was achieved at 1420 nm for −23 dBm input signal, whereas for an input signal power of −10 dBm it was 26 dB with a NF of 5.3 dB. The in-band OSNR of the proposed Bi-doped fiber amplifier (BDFA) was >22 dB from 1345 to 1460 nm for a −23 dBm input signal. The gain coefficient was found to be 0.04 dB/mW for a −23 dBm input signal. Also, the temperature dependent gain and NF performance of the BDFA within −40 to +60 °C were characterized. The temperature-dependent-gain (TDG) coefficient for a −23 dBm input signal was found to be −0.015 dB/°C at a signal wavelength of 1420 nm where the BDFA gain is maximum, while for an input signal power of −10 dBm it was −0.01 dB/°C at 1420 nm. The TDG coefficient of the proposed BDFA from 1350–1460 nm was in the range from −0.079 to −0.008 dB/°C. The BDFA gain and NF performance were also measured and compared using BPSFs with different unsaturable loss (UL) characteristics.