Computer-generated all-in-one wavelength combiner-splitter with ZrO₂-doped core planar lightwave circuit

Planar lightwave circuit (PLC) technology was originally designed for optical communication applications, and various optical communication devices with PLC technologies have been developed. Beyond its extensive use in optical communications, PLC technology is now being explored for applications in the visible light spectrum, and research is underway to enhance its high-power tolerance. In contrast to conventional GeO2-doped core PLCs, which suffer from refractive index variations under prolonged exposure to high-power visible light, ZrO2-doped core PLCs have emerged as a more robust alternative. However, they face significant manufacturing challenges, particularly in forming the narrow-gap waveguides, resulting in low yields that are especially evident in the optical circuit elements for coupling and splitting. Although various optical circuit elements for coupling and splitting in GeO2-doped core PLCs have been reported, the design freedom to flexibly combine multiple wavelengths or to tailor branching numbers and splitting ratios remains limited in ZrO2-doped core PLCs.