Narrow-band laser with an Nd3+-activated fibre

Two different configurations of narrow-band fibre lasers were investigated. One of them had a fibre reflector acting as a spectrally selective component: it consisted of two asymmetric Mach–Zehnder interferometers. In the second configuration use was made of a reflector based on a Bragg diffraction grating. In the former case it was found that lasing with a line width less than 1 nm and a total output power 70 mW was possible, whereas in the latter case an output power up to 15 mW was obtained for a line width not exceeding 100 MHz.