A highly-compact optical amplifier for densely-integrated communications systems

我们建议开发一种新型的极小形状因数(VSFF)片上光放大器。目前的VSFF放大器仅限于半导体光放大，使用昂贵的材料，并且受到高噪声和引起信号串扰的非线性的阻碍。作为领先的替代技术，掺铒光纤放大器(EDFA)在光学系统中提供低噪声和高增益，以实现高性能。 然而，用于制造这种放大器的二氧化硅光纤大约有几米长，包裹起来时不能弯曲得太紧，从而对设备的整体尺寸施加了限制。一种潜在的替代方案是掺铒波导放大器(EDWA)，它在低成本的硅衬底上制造掺铒波导，由于使用了高折射率的薄膜材料，允许大规模生产，尺寸减小了数量级，并且允许比二氧化硅更高的掺铒浓度。最近，我们使用了一种基于混合掺铒碲酸盐玻璃和氮化硅波导的新型平台来改进EDWA。我们的平台消除了EDWA过去阻碍其商业化的挑战，包括使用成熟的氮化硅技术的可重复制造方法，以及通过高折射率掺杂碲酸盐玻璃实现的紧凑外形系数的高增益。我们使用这个平台展示了高达5分贝的光学增益，显示了它的可行性。本项目需要解决的剩余挑战包括：a)在较长的螺旋波导中显示出高达20分贝的更高光增益；b)将光抽运和信号光的光纤-芯片耦合损耗降低至&lt；1分贝，以提高效率和噪声性能；c)在同一芯片和输入输出端口上展示具有光泵浦和信号多路复用功能的封装组件，其外形紧凑。这种紧凑型EDWA将在光通信网络、数据中心、高性能计算、人工智能、空间通信以及自动驾驶车辆的检测和测距中有广泛的应用。

We propose to develop a new very-small-form-factor (VSFF) optical amplifier on a chip. Current VSFF amplifiers are limited to semiconductor optical amplifiers (SOAs), which use costly materials and are hampered by high noise and nonlinearities which induce signal crosstalk. The leading alternative technology, erbium-doped fiber amplifiers (EDFAs) offer low noise and high gain for high performance in optical systems. However, the silica optical fiber used to build such amplifiers is on the order of meters long and cannot be bent too tightly when wrapped up, thereby imposing a limit on the overall size of the device. A potential alternative is the erbium-doped waveguide amplifier (EDWA), in which an erbium-doped waveguide is fabricated on a low-cost silicon substrate, allowing for large-scale production and orders of magnitude reduction in size because of the use of thin film materials with high refractive index and which allow for higher erbium dopant concentrations than silica. We have recently improved EDWAs using a novel platform based on hybrid erbium-doped tellurite glass and silicon nitride waveguides. Our platform removes past challenges with EDWAs which have prevented their commercialization, including reproducible fabrication methods using well-established silicon nitride technology, and high gain in a compact form factor enabled by the high refractive index doped tellurite glass. We have demonstrated optical gain of up to 5 dB using this platform, showing its viability. The remaining challenges to be addressed in this project include a) demonstrating higher optical gain of up to 20 dB in longer spiral waveguides; b) reducing the fiber-chip coupling loss to < 1 dB for optical pump and signal light to improve efficiency and noise performance; c) demonstrating a packaged component with optical pump and signal multiplexing on the same chip and input and output ports in a compact form factor. Such compact EDWAs will have wide-ranging applications in optical communications networks, data centers, high-performance computing, AI, space communications, and detection and ranging in self-driving vehicles.