Gallium phosphide (GaP) is an indirect-bandgap semiconductor used widely in solid-state lighting. Despite numerous intriguing optical properties—including large χ⁽²⁾ and χ⁽³⁾ coefficients, a high refractive index (>3) and transparency from visible to long-infrared wavelengths (0.55–11 μm)—its application as an integrated photonics material has been little studied. Here, we introduce GaP-on-insulator as a platform for nonlinear photonics, exploiting a direct wafer-bonding approach to realize integrated waveguides with 1.2 dB cm⁻¹ loss in the telecommunications C-band (on par with Si-on-insulator). High-quality (Q > 10⁵), grating-coupled ring resonators are fabricated and studied. Employing a modulation transfer approach, we obtain a direct experimental estimate of the nonlinear index of GaP at telecommunication wavelengths: n₂ = 1.1(3) × 10⁻¹⁷ m² W⁻¹. We also observe Kerr frequency comb generation in resonators with engineered dispersion. Parametric threshold powers as low as 3 mW are realized, followed by broadband (>100 nm) frequency combs with sub-THz spacing, frequency-doubled combs and, in a separate device, efficient Raman lasing. These results signal the emergence of GaP-on-insulator as a novel platform for integrated nonlinear photonics.

磷化镓（GaP）是一种间接带隙半导体，广泛用于固态照明中。尽管具有众多吸引人的光学特性，包括较大的χ ^（2）和χ ^（3）系数，高折射率（> 3）以及从可见光到长红外波长（0.55–11μm）的透明性，但它还是作为集成光子材料应用的很少研究。在这里，我们将绝缘体上的GaP引入到非线性光子学平台中，利用直接晶片键合方法实现电信C波段中损耗为1.2 dB cm ^-1的集成波导（与绝缘体上硅相当） 。高质量（Q  > 10 ⁵），制造并研究了光栅耦合环形谐振器。使用调制传递方法，我们获得了在电信波长下GaP非线性指数的直接实验估计：n ₂  = 1.1（3）×10 ^-17  m ²  W ^-1。我们还观察到具有工程色散的谐振器中Kerr频率梳的产生。实现了低至3 mW的参数阈值功率，随后是具有亚太赫兹间隔的宽带（> 100 nm）频率梳，倍频梳，以及在单独的设备中实现高效的拉曼激射。这些结果表明，绝缘体上GaP的出现成为了集成非线性光子学的新型平台。