Abstract
The non-Hermitian character of a gain-guided amplifier leads naturally to a description of the amplified field in terms of a nonorthogonal mode basis. We present a theoretical analysis, based on a nonorthogonal mode expansion, for the output of an amplifier with focused gain. The theory predicts that the gain-guided nature of the amplification process can lead to excess noise in the output of the amplifier. We then report the results of two experiments in which the output from a focused-gain Raman amplifier was measured. The experimental results are found to be in reasonable agreement with the nonorthogonal mode theory.
- Received 16 December 1992
DOI:https://doi.org/10.1103/PhysRevA.48.707
©1993 American Physical Society
