How to Excite a Photon?

So why haven't we been able to do on demand? Because as you just explained it, just exciting this metamaterial doesn't sound hard to me. But if we're trying to combine electronics and photonics together, wouldn't the entire system be limited by the capacities of the electronics? And so we wouldn't be really reaping the benefits of purely photonic systems. So how do we... I mean, for photonics, we need the layers to be very thin. Very precise thicknesses or dimensions are needed. That would be a challenge.