On-chip spectrometers hold significant promise in the development of laboratory-on-a-chip applications. However, the spectrometers usually require extra on-chip or off-chip photodetectors (PDs) to sense optical signals, resulting in increased footprints and costs. In this paper, we address this issue by proposing a fully on-chip spectrometer based on two-photon absorption (TPA) in a simple micro-ring resonator (MRR) configuration. While TPA is a commonly undesired phenomenon in conventional silicon devices due to its attached absorption losses and nonlinearity, we exploit it as a powerful and efficient tool for encoding spectral information, instead of using additional PDs. The input spectrum can be reconstructed from the sensed TPA current. Our proposed spectrometer achieves a bandwidth of 10 nm with a resolution of 0.4 nm while occupying a small footprint of only {16} \times {16}\;\unicode{x00B5}{\rm m}^2${16} \times {16}\;\unicode{x00B5}{\rm m}^2$, and the bandwidth can be further improved through several cascaded MRRs. This advancement could enable forward fully integrated and miniaturized spectrometers with low cost, which holds far-reaching applications in in situ biochemical analysis, remote sensing, and intelligent healthcare.

中文翻译：

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基于双光子吸收的小型化计算光谱仪

片上光谱仪在片上实验室应用的开发中具有重大前景。然而，光谱仪通常需要额外的片上或片外光电探测器 (PD) 来感测光信号，从而导致占地面积和成本增加。在本文中，我们通过提出一种基于简单微环谐振器（MRR）配置中的双光子吸收（TPA）的全片上光谱仪来解决这个问题。虽然 TPA 由于其附加的吸收损耗和非线性而在传统硅器件中是一种常见的不良现象，但我们将其用作编码光谱信息的强大而有效的工具，而不是使用额外的 PD。输入频谱可以根据感测到的 TPA 电流重建。我们提出的光谱仪实现了 10 nm 的带宽和 0.4 nm 的分辨率，同时占用的空间仅为{16} \times {16}\;\unicode{x00B5}{\rm m}^2${16} \times {16}\;\unicode{x00B5}{\rm m}^2$，并且带宽可以为通过几个级联 MRR 进一步改进。这一进步可以实现低成本的前向完全集成和小型化光谱仪，在原位生化分析、遥感和智能医疗保健方面具有深远的应用。