I'm not really sure I'd call two reverse-parallel (DC) LEDs an AC LED. The design in figure 1b seems basically equivalent to a dropper capacitor[1] and DC recti

I'm not really sure I'd call two reverse-parallel (DC) LEDs an AC LED. The design in figure 1b seems basically equivalent to a dropper capacitor[1] and DC rectifier feeding standard LEDS (expect you're lighting different LEDs on each half-wave instead of the same ones), which us how a lot of LED lamps are already driven. [1] https://en.wikipedia.org/wiki/Capacitive_power_supply https://en.wikipedia.org/wiki/Capacitive_power_supply