electromagnetic radiation - Could an oscillator at a high enough frequency produce light instead of radio waves?

Considering that light is in the 400-800 THz range, if you had an electrical oscillator that ran at that frequency connected to an aerial of some sort, would the antenna emit visible light, in the same manner that radio waves emit radio "light"?

We have specialized transistors that can run at many hundreds of gigahertz, and even some that work up to the few-terahertz regime. I can fairly easily see further advances perhaps producing oscillators at a hundred THz, which would be well into the infrared range, if not visible light.