Cost-efficient and easily integrable broadband mid-infrared (mid-IR) sources would significantly enhance the application space of photonic integrated circuits (PICs). Thermal incandescent sources are superior to other common mid-IR emitters based on semiconductor materials in terms of PIC compatibility, manufacturing costs, and bandwidth. Ideal thermal emitters would radiate directly into the desired modes of the PIC waveguides via near-field coupling and would be stable at very high temperatures. Graphene is a semimetallic two-dimensional material with comparable emissivity to thin metallic thermal emitters. It allows maximum coupling into waveguides by placing it directly into their evanescent fields. Here, we demonstrate graphene mid-IR emitters integrated with photonic waveguides that couple directly into the fundamental mode of silicon waveguides designed to work in the so-called “fingerprint region” relevant for gas sensing. High broadband emission intensity is observed at the waveguide-integrated graphene emitter. The emission at the output grating couplers confirms successful coupling into the waveguide mode. Thermal simulations predict emitter temperatures up to 1000 °C, where the blackbody radiation covers the mid-IR region. A coupling efficiency η, defined as the light emitted into the waveguide divided by the total emission, of up to 68% is estimated, superior to data published for other waveguide-integrated emitters.

中文翻译：

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石墨烯热红外发射器集成到硅光子波导中


经济高效且易于集成的宽带中红外（mid-IR）源将显着扩大光子集成电路（PIC）的应用空间。热白炽光源在 PIC 兼容性、制造成本和带宽方面优于其他基于半导体材料的常见中红外发射器。理想的热发射器将通过近场耦合直接辐射到 PIC 波导的所需模式，并且在非常高的温度下保持稳定。石墨烯是一种半金属二维材料，其发射率与薄金属热发射体相当。通过将其直接放入波导的渐逝场中，它可以最大程度地耦合到波导中。在这里，我们展示了与光子波导集成的石墨烯中红外发射器，该发射器直接耦合到硅波导的基本模式，设计用于与气体传感相关的所谓“指纹区域”。在波导集成石墨烯发射器处观察到高宽带发射强度。输出光栅耦合器处的发射证实了成功耦合到波导模式。热模拟预测发射器温度高达 1000 °C，其中黑体辐射覆盖中红外区域。耦合效率 η（定义为发射到波导中的光除以总发射量）估计高达 68%，优于其他波导集成发射器公布的数据。