http://www.angelfire.com/art/jedzelex/zelda_temple_light.html

Dan: Here's the story, as it was explained to me by the designers of the game when I was in Japan working on the text.

The Temple of Light is the place where Link speaks to Rauru, with the different medallion symbols on the floor. It exists in the Sacred Realm (also referred to as the Golden Land in other versions of the story), which is a kind of parallel dimension to the real world of Hyrule and was created by the power of the Triforce.

When Ganondorf entered the Sacred Realm (after Link opened it by pulling the Master Sword out of the Pedestal of Time) and stole the Triforce, his evil wishes turned the Sacred Realm into the Dark World. Only the Temple of Light was able to resist Ganondorf's power and remain pure.

Think of the Temple of Light as the end of a passage that leads from Hyrule to the Sacred Realm, with the other entry point being the Temple of Time.

In short, the Temple of Light does exist in (Ocarina of Time), but it's not really somewhere you can explore since it only appears in the cinema scenes.