High‐Gain Waveguide Amplifiers in Ge25Sb10S65Photonics Heterogeneous Integration with Erbium‐Doped Al2O3Thin Films

Abstract High‐efficiency optical waveguide amplifiers are becoming desperately desirable in integrated photonics to provide sufficient power compensations. Various material platforms have been employed to realize on‐chip waveguide amplifiers to date. Chalcogenide glasses (ChGs), as one of the well‐developed and promising optical platforms, have been extensively studied due to the excellent properties of low loss and high third‐order nonlinearity. However, the performances of their waveguide amplifiers are far from expectations on account of the intrinsic natures of low rare‐earth ion solubility, low luminous efficiency in chalcogenide hosts as well as the high photoinduced absorption loss in certain compounds. Here, a heterogeneous optical amplifier is proposed and demonstrated in an alternative Ge 25 Sb 10 S 65 (GeSbS) waveguide via integration with an erbium‐doped aluminum oxide (Al 2 O 3 ) layer for the first time. A total 4.6 cm long spiral waveguide exhibits an internal net gain as high as 6.27 ± 0.618 dB at 1533 nm and a broad gain bandwidth over 40 nm ‐ ranging from 1520 nm to 1560 nm upon 1480 nm pumping. It is believed that this heterogeneous configuration will greatly enrich the functionality and versatility of the ChGs integrated photonics.