  Programmable spatiotemporal control of light is crucial for advancements in
optical communications, imaging, and quantum technologies. Commercial spatial
light modulators (SLMs) typically have megapixel-scale apertures but are
limited to ~kHz operational speeds. Developing a device that controls a similar
number of spatial modes at high speeds could potentially transform fields such
as imaging through scattering media, quantum computing with cold atoms and
ions, and high-speed machine vision, but to date remains an open challenge. In
this work we introduce and demonstrate a free-form, resonant electro-optic (EO)
modulator with megapixel apertures using CMOS integration. The optical layer
features a Lithium Niobate (LN) thin-film integrated with a photonic crystal
(PhC), yielding a guided mode resonance (GMR) with a Q-factor>1000, a field
overlap coefficient ~90% and a 1.6 GHz 3-dB modulation bandwidth (detector
limited). To realize a free-form and scalable SLM, we fabricate the PhC via
interference lithography and develop a procedure to bond the device to a
megapixel CMOS backplane. We identify limitations in existing EO materials and
CMOS backplanes that must be overcome to simultaneously achieve
megapixel-scale, GHz-rate operation. The `LN on Silicon' (LNoS) architecture we
present is a blueprint towards realizing such devices.
