AI 中文总结
该研究开发了一种片上扫频光源双光梳光谱仪，采用两个单向跑道型半导体激光器，实现了8 μm附近32 cm⁻¹范围的光谱采样，通过基准测试和HITRAN模拟验证了其性能，具备小型化及抗光反馈优势。
AI 中文摘要
双光梳光谱学（DCS）通过两个相互失谐的光频梳的干涉，将光谱下转换到射频（RF）域，从而实现高速、高分辨率光谱测量。要准确分辨窄分子吸收特征，需要由具有长往返时间的大型激光腔产生的密排光梳齿，这阻碍了高分辨率光谱仪的小型化。本研究通过展示一种采用集成在同一芯片上的两个单向跑道型半导体激光器的扫频光源双光梳光谱仪，规避了这一限制。在激光腔14.3 GHz的往返频率下，通过强射频注入产生行波光频梳，且可通过改变激光器驱动电流对其进行连续频率调谐。这实现了在以8 μm为中心的32 cm⁻¹范围内的连续光谱采样，有效采样间隔约为80 MHz。两个光频梳的输出被耦合到同一单片集成光耦合器中，在组合光束探测样品前自动实现共线对准。研究将该光谱仪与外腔可调谐激光器进行基准测试，并利用HITRAN数据库对1.25%一氧化二氮的模拟验证其性能。最后，单向光梳架构抑制了光反馈的有害影响，即使在故意引入强反馈的情况下，仍能获得相当的残差。更广泛而言，小型化的益处不仅限于减少占地面积：芯片级集成实现了新型电和光控制方式，可从根本上改变双光梳光谱仪的运行方式。
英文摘要
Dual-comb spectroscopy (DCS) enables high-speed, high-resolution spectroscopy by down-converting optical spectra to the radio-frequency (RF) domain through the interference of two mutually detuned frequency combs. Accurately resolving narrow molecular absorption features requires closely spaced comb lines generated by large laser cavities with long round-trip times, thereby hindering the miniaturization of high-resolution spectrometers. Here, we circumvent this limitation by demonstrating a swept-source dual-comb spectrometer using two unidirectional racetrack semiconductor lasers integrated on the same chip. The traveling-wave frequency combs are generated by strong RF injection at the laser cavity round-trip frequency of 14.3~GHz and are continuously tuned in frequency by varying the laser drive currents. This enables continuous spectral sampling over a 32~cm$^{-1}$ range centered near 8~\textmu m, with an effective sampling interval of approximately 80~MHz. The outputs of both combs are coupled into the same monolithically integrated light coupler, providing automatic collinear alignment before the combined beam interrogates the sample. We benchmark the spectrometer against an external-cavity tunable laser and validate its performance using HITRAN simulations for 1.25\% nitrous oxide. Finally, the unidirectional comb architecture suppresses the detrimental effects of optical feedback, yielding comparable residuals even under deliberately introduced strong feedback. More broadly, the benefits of miniaturization extend beyond reduced footprint: chip-scale integration enables new forms of electrical and optical control that can fundamentally change how dual-comb spectrometers are operated.
CommentsThese authors contributed equally: Johannes Fuchsberger, Theodore P. Letsou. 24 pages, 4 figures
