Low noise, all-optical gain controlled Er3+ doped fibre amplifier using asymmetric control laser cavity design

The authors demonstrate an Er³⁺ doped fibre amplifier with all-optical, automatic gain control and with near quantum limited, 1480 nm pumped noise performance. The amplifier gain is controlled by in-band laser action, and two design considerations are established for optimum noise performance: the control laser wavelength should be located in a region of high amplifier gain, and the laser cavity should be constructed to be as asymmetric as possible, ensuring minimum laser power at the signal input end of the amplifier