How to select the material for high speed circuit board?

Recently I need to disign a test board for a laser driver circuit which works at about 40 Gb/s. I am not very clear about the requirment for the materail of high speed circiuit board . Could anyone give me some guide?

Thanks!

This will help you:
http://www.speedingedge.com/PDF-File...als_RickH2.pdf