  Organic electro-optic (OEO) materials have demonstrated promising performance
in developing electro-optic phase shifters (EOPS) and modulators compared to
their inorganic counterparts. Integration with other devices in a silicon
photonic (SiP) process, simple nanofabrication, and temperature/aging
robustness remain to be developed for this class of hybrid material platforms.
In particular, electro-optic (EO) polymers need an electro-thermal poling
method, which has limited their potential and utilization in large-scale SiP.
Devices made of paraelectric nematic liquid crystals (PN-LC), another primary
type of OEO material, feature a very efficient but slow phase shift mechanism.
We present a general-purpose EOPS that applies to various modulator embodiments
to address these concerns. Based on that, we report a GHz-fast phase shift in a
newly discovered family of OEO, namely ferroelectric nematic liquid crystals
(FN-LC), which finally enables liquid crystals to have significant second-order
nonlinear optical coefficients and associated Pockels effect. The new material
avoids poling issues associated with EO polymers and can pave the way for
hybrid silicon-OEO systems with CMOS-foundry compatibility. Furthermore, we
propose a finger-loaded, non-slotted waveguide that enhances light-matter
interaction, allowing us to achieve DC and AC modulation efficiencies of
$\approx$ 0.25 V.mm and 25.7 V.mm, respectively, an on-chip insertion loss of
$\approx$ 4 dB, and an EO bandwidth of f$_{-6dB}$ >4.18 GHz. The remaining
figures of merit for our poling-free EOPS are equivalent to EO polymer-enabled
devices with fewer manufacturing difficulties. We demonstrate an electrically
and photonically packaged chip that contains >100 silicon-FN-LC modulators to
evaluate the large-scale integration of our poling-free phase shifters and
modulators.
