Novel pumping scheme of Holmium doped fiber amplifiers operating around [formula omitted] using [formula omitted] lasers exploiting cascaded fiber lasers

Abstract

The optical communication window around 2μm is attracting significant research attention for future optical communication systems as an extension to the C-, L-, and U-bands. One of the research topics in the 2μm region is optical amplifiers. Holmium-doped fiber amplifier (HDFA) is a suitable candidate for amplifying signals in this region. However, the pump laser for Holmium-doped fiber (HDF) is expensive and not widely available. In this work, we propose through numerical simulations, a novel pumping scheme to pump the HDF using commercially available 1.48μm lasers by exploiting cascaded fiber lasers made up of Erbium-doped fiber (EDF) and Thulium-doped fiber (TDF). The first fiber uses a commercially available 1.48μm laser to pump a piece of EDF to generate a 1.62μm continuous wave (CW) laser. This 1.62μm CW laser is used to pump a piece of TDF in the second fiber laser to create a 1.95μm CW laser that is used to pump the HDF. The HDFA can be used to amplify modulated optical signals in the 2μm wavelength range. A small-signal gain of 52.5 dB, 46.2 dB, and 32.6 dB can be achieved for input signal powers of −30 dBm, −15 dBm, and 0 dBm, respectively, at 2.032μm using a 5 W laser diode pump at 1.48μm. A noise figure (NF) of 7.5 dB, 6.6 dB, and 5.58 dB has been observed for input signal power of −30 dBm, −15 dBm, and 0 dBm, respectively at 2.032μm.