Front-end electro-optical interfaces for CMS HCAL

The CMS experiment is a complex instrument to study particle physics at the energy frontier. An important detector subsystem within CMS is the hadron calorimeter or HCAL, consisting of four subsystems that cover the kinematic region |/spl eta/|<5. This paper provides details of the electro-optical interfaces for the central barrel subsystem that operates in a region of high magnetic field and converts scintillation signals from megatile sampling layers to lower geometry for energy measurement.