Enhanced Erbium–Zirconia–Yttria–Aluminum Co-Doped Fiber Amplifier

An efficient optical amplifier is demonstrated using an improved erbium-zirconia-yttria-aluminum co-doped fiber (Zr-EDF) as the gain medium. With a combination of both Zr and Al, we could achieve a high erbium doping concentration with an absorption loss of around 80.0 dB/m at 980 nm. The Zr-EDF is obtained from a fiber preform, which is fabricated in a ternary glass host, i.e., a zirconia-yttria-aluminum co-doped silica fiber, using a modified chemical vapor deposition, in conjunction with a solution doping process. At the optimum length of 1 m, the Zr-EDF amplifier produces a flat gain of 38 dB within a wavelength region between 1530 and 1565 nm with a gain variation of less than 3 dB when the input signal power and 980 nm pump power are fixed at $-$30 dBm and 130 mW, respectively. The highest gain of 40.3 dB is obtained at 1560 nm wavelength. Compared with the previous Zr-EDF amplifier, the proposed Zr-EDFA shows improved gain, particularly at longer wavelengths. The gain is enhanced by about 15.8 dB at a wavelength of 1560 nm for an input signal of $-$30 dBm.