FIBEROPTIC RAMAN AMPLIFIER OF SIGNALS AT THE 1.3 MU-M WAVELENGTH, PUMPED BY A CR4-FORSTERITE CRYSTAL LASER()

A report is given of the experimental results of an investigation of t he parameters of a fibre-optic Raman amplifier pumped by radiation fro m a highly stable laser with a forsterite (Mg2SiO4) crystal doped with Cr4+ ions, The non-absorbed part of the pump radiation was returned t o an active fibre waveguide by a fibre Bragg grating in order to incre ase the amplifier efficiency. A high measurement precision was ensured by a system for stabilisation of the pump power coupled into the acti ve fibre, When the pump power was 800 mW and the noise factor was 4 dB , the gain was 30 dB; when the gain was 15 dB, the gain saturation pow er-expressed in terms of the output signal-was 15 dBm.