YES, I did say 1TB optical disc!  New develpoments by TDK has created such a thing.  TDK created a dielectric material as the reflection film that provides a high light transmittance in order incident light to efficiently reach as far as innermost layer and produce a clear eye pattern (read-out signal).

The result is impressive: While the light transmittance of a single layer is 95.1%, it becomes just 72.6% for the total 16 layers of the disc. The specific material has been already used in the currently available Blu-ray discs, according to TDK. 

Imagin the possibilities!