Numerous applications in quantum and classical optics require scalable,
high-speed modulators that cover visible-NIR wavelengths with low footprint,
drive voltage (V) and power dissipation. A critical figure of merit for
electro-optic (EO) modulators is the transmission change per voltage, dT/dV.
Conventional approaches in wave-guided modulators seek to maximize dT/dV by the
selection of a high EO coefficient or a longer light-material interaction, but
are ultimately limited by nonlinear material properties and material losses,
respectively. Optical and RF resonances can improve dT/dV, but introduce added
challenges in terms of speed and spectral tuning, especially for high-Q
photonic cavity resonances. Here, we introduce a cavity-based EO modulator to
solve both trade-offs in a piezo-strained photonic crystal cavity. Our approach
concentrates the displacement of a piezo-electric actuator of length L and a
given piezoelectric coefficient into the PhCC, resulting in dT/dV proportional
to L under fixed material loss. Secondly, we employ a material deformation that
is programmable under a "read-write" protocol with a continuous, repeatable
tuning range of 5 GHz and a maximum non-volatile excursion of 8 GHz. In
telecom-band demonstrations, we measure a fundamental mode linewidth = 5.4 GHz,
with voltage response 177 MHz/V corresponding to 40 GHz for voltage spanning
-120 to 120 V, 3dB-modulation bandwidth of 3.2 MHz broadband DC-AC, and 142 MHz
for resonant operation near 2.8 GHz operation, optical extinction down to
min(log(T)) = -25 dB via Michelson-type interference, and an energy consumption
down to 0.17 nW/GHz. The strain-enhancement methods presented here are
applicable to study and control other strain-sensitive systems