hi benyahia,,,
for creating an optical frequency comb refer this link first…
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiEk73-gbbLAhUJJI4KHbK7D3MQFgggMAA&url=http%3A%2F%2Foptiwave.com%2Fwp-content%2Fuploads%2F2014%2F10%2F1_2171.pdf&usg=AFQjCNHUoYDR29MHPO7F0D7UphJgGPD_gQ&sig2=sFV9i65791jA5JCefShfGQ&bvm=bv.116573086,d.c2E