  Nonlinear optical effects have been studied extensively in microresonators as
more photonics applications transition to integrated on-chip platforms. Due to
low optical losses and small mode volumes, microresonators are demonstrably the
state-of-the-art platform for second harmonic generation (SHG). However, the
working bandwidth of such microresonator-based devices are relatively small,
presenting a challenge for applications where a specifically targeted
wavelength needs to be addressed. In this work, we analyzed the phase-matching
window and resonance wavelength with respect to varying microring width, radius
and temperature. A chip with precise design parameters was fabricated with
phase-matching realized at the exact wavelength of two-photon transition of
85-Rubidium. This procedure can be generalized to any target pump wavelength in
the telecom-band with picometer precision.
