Experimental Investigation On Multimode Quartz Fibre Phase Conjugation Using Sbs

The beam quality of solid-state lasers with high average power can be greatly improved using phase conjugators based on stimulated Brillouin scattering (SBS). The common phase conjugators used till now are liquid or gas cells. Using SBS in glass fibres as phase conjugators the field of applications can be expended. The long interaction length and small cross-sections of the fibres result in an appreciable reduction of SBS threshold and avoid optical breakdown which could happen in liquids and gases at high input energies. Other advantages of glass fibre phase conjugators are harmlessness and easy handling. We have experimentally investigated a phase conjugator based on SBS obtained in an undoped quartz fibre with core diameter of 200 mu m. The SBS threshold reflectivity and phase conjugation capability were measured with 18 ns pulses at 1.06 mu m wave length with different input energies.