Technique to develop active devices by modifying Brillouin gain spectrum

A simple technique to reshape the Brillouin gain spectrum is based on the superposition of the Brillouin scattering spectra from several concatenated optical fibres. Different and well defined Brillouin gain spectra can be obtained from each singlemode fibre, when they are pumped at the same optical pump radiation. Furthermore, with this technique, a customised Brillouin gain spectral response can be obtained by choosing the singlemode fibres properly. Thus, active devices such as filters, amplifiers and lasers with narrow band and customised band can be developed. To check the idea experimentally, an active device with a like dasiaMdasia spectral response, with a bandwidth of 280dasiaMHz at 3dasiadB and a reject band placed in 10.78dasiaGHz from the pump wavelength, is proposed and demonstrated. Four different pieces of singlemode fibre, each 5dasiam long, were used.