This brief presents an ultrasonically powered micro-system for deep tissue optogenetic stimulation. The developed system is composed of a Base for Powering and Controlling (BPC) and an implantable Dust for optogenetics and drug delivery. The Dust consists of a piezoelectric crystal, a rectifier chip, and a micro-scale custom-designed light-emitting-diode (μ LED) integrated, miniaturized, and envisioned to be used for freely moving animal studies. The proposed Dust operates in frequencies up to 5 MHz, power levels in the 0-10 mW range, achieves start-up within 1.8~μ s at 2.9 MHz operating frequency at 14.4 mW/mm2 ultrasound power density, and 98.1% chip efficiency at 2 mW input power. With the BPC implemented and attached to ( 500~μ m )3 PZT4 crystals, set to 60 V at 2.8 MHz operating frequency at 3 mm distance in demineralized water, the dust delivered up to 6 mW to its load (μ LED for optogenetics), which translates to 0.11% total system efficiency.