Nonlinear optics plays an important role in many areas of science and technology. The advance of nonlinear optics is empowered by the discovery and utilization of materials with growing optical nonlinearity. Here we demonstrate an indium gallium phosphide (InGaP) integrated photonics platform for broadband, ultra-efficient second-order nonlinear optics. The InGaP nanophotonic waveguide enables second-harmonic generation with a normalized efficiency of 128, 000%/W/cm² at 1.55 μm pump wavelength, nearly two orders of magnitude higher than the state of the art in the telecommunication C band. Further, we realize an ultra-bright, broadband time-energy entangled photon source with a pair generation rate of 97 GHz/mW and a bandwidth of 115 nm centered at the telecommunication C band. The InGaP entangled photon source shows high coincidence-to-accidental counts ratio CAR > 10⁴ and two-photon interference visibility > 98%. The InGaP second-order nonlinear photonics platform will have wide-ranging implications for non-classical light generation, optical signal processing, and quantum networking.

非线性光学在科学和技术的许多领域都发挥着重要作用。非线性光学的进步得益于光学非线性度不断提高的材料的发现和利用。在这里，我们展示了一个用于宽带、超高效二阶非线性光学的磷化铟镓 （InGaP） 集成光子学平台。InGaP 纳米光子波导可在 1.55 μm 泵浦波长下以 128， 000%/W/cm² 的归一化效率产生二次谐波，比电信 C 波段的最新技术高出近两个数量级。此外，我们实现了一种超亮、宽带时间能量纠缠光子源，其对产生速率为 97 GHz/mW，带宽为 115 nm，以电信 C 波段为中心。InGaP 纠缠光子源显示出高符合与意外计数比 CAR > 10⁴ 和双光子干涉能见度 > 98%。InGaP 二阶非线性光子学平台将对非经典光产生、光信号处理和量子网络产生广泛的影响。