  The development of manufacturable and scalable integrated nonlinear photonic
materials is driving key technologies in diverse areas such as high-speed
communications, signal processing, sensing, and quantum information. Here, we
demonstrate a novel nonlinear platform -- InGaP-on-insulator -- optimized for
visible-to-telecommunication wavelength $\chi^{\left(2\right)}$ nonlinear
optical processes. In this work, we detail our 100-mm wafer-scale
InGaP-on-insulator fabrication process realized via wafer bonding, optical
lithography, and dry-etching techniques. The resulting wafers yield 1000s of
components in each fabrication cycle, with initial designs that include
chip-to-fiber couplers, 12.5-cm-long nested spiral waveguides, and arrays of
microring resonators with free-spectral ranges spanning 400-900 GHz. We
demonstrate intrinsic resonator quality factors as high as 324,000 (440,000)
for single-resonance (split-resonance) modes near 1550 nm corresponding to 1.56
dB cm$^{-1}$ (1.22 dB cm$^{-1}$) propagation loss. We analyze the loss versus
waveguide width and resonator radius to establish the operating regime for
optimal 775-to-1550 nm phase matching. By combining the high
$\chi^{\left(2\right)}$ and $\chi^{\left(3\right)}$ optical nonlinearity of
InGaP with wafer-scale fabrication and low propagation loss, these results open
promising possibilities for entangled-photon, multi-photon, and squeezed light
generation.
