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Optomechanical Cavities for All-Optical Photothermal Sensing
ACS Photonics ( IF 6.5 ) Pub Date : 2018-06-26 00:00:00 , DOI: 10.1021/acsphotonics.8b00452
Marcel W. Pruessner 1 , Doewon Park 1 , Todd H. Stievater 1 , Dmitry A. Kozak 1 , William S. Rabinovich 1
Affiliation  

Cavity optomechanics enables strong coupling of optics and mechanics. Although remarkable progress has been made, practical applications of cavity optomechanics are only recently being realized. In this work we propose an all-optical sensing technique enabling the measurement of photothermally induced strains with ultrahigh-resolution. We demonstrate an optomechanical sensor consisting of a silicon nitride (Si3N4) microring cavity that is evanescently coupled to a suspended SiNx micromechanical (MEMS) oscillator. Experiments show that MEMS resonances are excited purely via cavity-enhanced gradient optical forces. However, small levels of absorption in the oscillator result in photothermally induced strains that shift the mechanical resonance frequencies. By measuring absorption-induced frequency shifts our technique enables high-resolution with nanostrain sensitivity corresponding to fJ-levels of absorption. As a demonstration, we perform absorption spectroscopy on the MEMS device and measure the known Si–H absorption feature of deposited silicon nitride. The unprecedented sensitivity enabled by absorption-induced frequency shifts enables entirely new sensors in fields ranging from materials and chemical sensing to bolometers and imaging arrays.

中文翻译:

用于全光学光热传感的光机械腔

腔光学机械实现了光学和机械的强大耦合。尽管已经取得了显着的进步,但腔体光力学的实际应用直到最近才被实现。在这项工作中,我们提出了一种全光学传感技术,能够以超高分辨率测量光热诱导的菌株。我们演示了一个光机械传感器,该传感器由氮化硅(Si 3 N 4)微环腔构成,该微环腔e逝耦合到悬浮的SiN x微机械(MEMS)振荡器。实验表明,MEMS谐振纯粹是通过腔增强的梯度光学力来激发的。但是,振荡器中的少量吸收会导致光热感应应变,从而使机械共振频率发生偏移。通过测量吸收引起的频移,我们的技术可实现高分辨率,且纳米应变灵敏度与吸收的fJ级相对应。作为演示,我们在MEMS器件上进行吸收光谱分析,并测量沉积的氮化硅的已知Si–H吸收特征。吸收引起的频移带来了前所未有的灵敏度,从而使全新的传感器在从材料和化学传感到辐射热测量仪和成像阵列等各个领域都可以使用。
更新日期:2018-06-26
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