Deep Blue Light was originally called "Electric Light". It was the only other light source besides Torch. This is no longer true, with the introduction of 8-channel lighting in the 1.1 Pre-Alpha Patch. You can only delete light blocks by adding a block over it, then deleting the block that was placed.
This light has been in the game since the release on April 8, 2011 as it was not changed with all the other lamps.