Chalcogenide perovskites have emerged as lead-free, stable photovoltaic materials, having promising optoelectronic properties. A next step in engineering new electro-optic perovskites includes exploring silicon-based compounds, since the stereochemical activity of the s2 lone pair increases in moving up the periodic table. This activity leads to the non-centrosymmetry in the nickel compounds and so can be expected to lead to greater asymmetries in silicon compounds. The nonlinear response from the spontaneous dipole moment within a perovskite unit cell can result in photons that carry an energy different from the exciting laser. By mixing or splitting the energies from the incoming photons, coherent light wave with specific wavelengths is created through various mechanisms, such as SHG, sum- and difference- frequency generation (SFG and DFG), and optical parametric oscillation (OPO). Bulk perovskite oxide single crystals have been utilized in various nonlinear photonic systems, including LiNbO3 and LaTiO3. Applying the quasi-phase matching on these perovskite oxide crystals, nonlinear frequency conversion becomes more efficient and provides coherent light sources over a broad spectrum. In addition, the nonlinear optical method can generate an entangled photon-pair through the parametric down-conversion, which is critical for the development of quantum communication and networking. Low dimensional materials open an opportunity for compact optical cavities for Purcell enhancement of single photon down conversion (SPDC).