Advanced LIGO Optical Configuration and Prototyping Effort,
Published in
the Proceedings of the 4th Amaldi Conference on Gravitational Waves,
Classical and Quantum Gravity 19, 1575 (2002).
The
originally submitted paper, containing much more detail on the
status of the 40m upgrade and on simulation tools,
was deemed unnecessarily detailed and technical.
Thus, it may be of more interest to you.