Polarization-dependent gain in bismuth-doped phospho- and germanosilicate fiber amplifiers

Area of Science:

• Optical Fiber Amplifiers
• Photonics
• Materials Science

Background:

• Bismuth-doped fiber amplifiers (BDFAs) are crucial for optical amplification.
• Understanding polarization-dependent gain (PDG) is essential for amplifier performance.
• PANDA-type fibers offer unique properties for fiber amplifier development.

Purpose of the Study:

• To investigate the polarization-dependent gain (PDG) effect in bismuth-doped fiber amplifiers (BDFAs).
• To compare PDG in BDFAs using phospho- and germanosilicate core fibers.
• To correlate experimental PDG results with simulation models based on bismuth active centers (BACs) anisotropy.

Main Methods:

• Experimental study of PDG in core-pumped BDFAs utilizing PANDA-type phospho- and germanosilicate fibers.
• Measurement of gain difference between orthogonal signal polarizations.
• Development and application of a simulation model based on the anisotropy parameter of BACs, derived from luminescence polarization.

Main Results:

• PDG values in the range of 2.5-3 dB were observed for BDFAs with over 20 dB total gain.
• The PDG effect was found to be more pronounced in BDFAs employing germanosilicate fibers compared to phosphosilicate fibers.
• Experimental results closely matched simulation data, validating the model's accuracy in predicting PDG based on BACs anisotropy (9-12% for Si, 18-22% for P).

Conclusions:

• The study quantifies PDG in BDFAs, highlighting its dependence on core fiber material.
• Germanosilicate core fibers exhibit a stronger PDG effect, suggesting specific applications or design considerations.
• The findings provide valuable data for optimizing BDFA performance and understanding the structural properties of bismuth active centers.