384 25 Fiber Grating Lasers and Amplifiers Gain 20 F and gain / dB F front loss F back loss F modeleid Laser: 1530nm 10 Pump: 1480nm 65mW Length: 20m 0 1540 1545 1550 1555 1560 1565 1570 15 5 Wavelength / nm Figure 8.35 Gain and noise figure for an AGC amplifier in two cavity implementations (courtesy J. Massicott, BT Laboratories). laser to be in a high-gain region of the spectrum requiring a correspondingly high cavity loss. Figure 8.35 shows the measured gain and noise figures of an AGC amplifier