A novel EDFA module using a variable-PBS with 3 dB noise figure reduction

The dominant contribution to noise figure (NF) of Er³⁺-doped fiber amplifiers (EDFA) is ASE (amplified spontaneous emission) power level, which is determined by the ASE power level. For NF reduction of an optical amplifier, different techniques have been used. One of the widely used technique is incorporating a narrow linewidth filter to filter out the broadband ASE, which yields a typical NF reduction of 0.5 dB with a ~3 dB insertion loss. In this paper, we report a new technique utilizing a variable-polarization beam splitter (VPBS) in an EDFA for up to 3 dB NF reduction