Superconducting nanowire single-photon detectors promise efficient ($$100\%)andfast($$Gcps) detection of light at the single-photon level. They constitute one of the building blocks to realize integrated quantum optical circuits in a waveguide architecture. The optical response of single-photon detectors, however, is limited to measure only the presence of photons. It misses the capability to resolve the spectrum of a possible broadband illumination. In this work, we propose the optical design for a superconducting nanowire single-photon spectrometer in an integrated optical platform. We exploit a cascade of cavities with different resonance wavelengths side-coupled to a photonic crystal bus waveguide. This allows to demultiplex different wavelengths into different spatial regions, where individual superconducting nanowires that measure the presence of single photons are placed next to these cavities. We employ temporal coupled-mode theory to derive the optimal conditions to achieve a high absorption efficiency in the nanowire with fine spectral resolution. It is shown that the use of a mirror at the end of the cascaded system that terminates the photonic crystal bus waveguide increases the absorption efficiency up to unity, in principle, in the absence of loss. The expected response is demonstrated by full-wave simulations for both two-dimensional and three-dimensional structures. Absorption efficiencies of about $80\%$ are achieved both in two-dimensional structures for four cascaded cavities and in three-dimensional structures for two cascaded cavities. The achieved spectral resolution is about $1\mathrm{\text{nm}}$. We expect that the proposed setup, both analytically studied and numerically demonstrated in this work, offers a great impetus for future quantum nanophotonic on-chip technologies.

中文翻译：

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利用级联光子晶体腔的超导纳米线单光子光谱仪

超导纳米线单光子探测器有望实现高效（$$100％）\mathrm{一种}ñdF\mathrm{一种}sŤ（$$ Gcps）检测单光子级的光。它们构成了在波导架构中实现集成量子光学电路的基本要素之一。但是，单光子检测器的光学响应仅限于仅测量光子的存在。它缺少解决可能的宽带照明光谱的能力。在这项工作中，我们为集成光学平台中的超导纳米线单光子光谱仪提出了光学设计。我们利用侧向耦合到光子晶体总线波导的谐振波长不同的级联腔。这允许将不同的波长多路分解为不同的空间区域，在这些空间中，将测量单个光子存在的单个超导纳米线放置在这些腔中。我们采用时间耦合模式理论来推导最佳条件，以实现具有精细光谱分辨率的纳米线的高吸收效率。示出了，在级联系统的末端处终止于光子晶体总线波导的反射镜的使用，原则上在没有损耗的情况下将吸收效率提高到最大。二维和三维结构的全波仿真证明了预期的响应。吸收效率约 在没有损失的情况下。二维和三维结构的全波仿真证明了预期的响应。吸收效率约 在没有损失的情况下。二维和三维结构的全波仿真证明了预期的响应。吸收效率约$80％$对于四个级联的腔体，在二维结构中，对于两个级联的腔体，在三维结构中都可以实现。达到的光谱分辨率约为$\mathrm{1个}\mathrm{\text{纳米}}$。我们希望在这项工作中经过分析研究和数值演示的拟议装置将为未来的量子纳米光子片上技术提供强大动力。