分类： 光学 >> 量子光学 提交时间： 2023-02-19
Jian Li
Jie Pang
Zhen-dong Yan
Junghoon Jahng
Jin Li
William Morrison
Jing Liang
Qing-Ying Zhang
Xing-Hua Xia
摘要： Tip enhanced IR spectra and imaging have been widely used in cutting-edge studies for the in-depth understanding of the composition, structure and function of interfaces at the nanoscale. However, molecular monolayer sensitivity has only been demonstrated on solid/gas interfaces. In aqueous environment, the reduced sensitivity due to strong damping of the cantilever oscillation and background IR absorption extremely limits the practical applications of tip enhanced IR nanospectroscopy. Here, we demonstrate hypersensitive nanoscale IR spectra and imaging in aqueous environment with the combination of photoinduced force (PiF) microscopy and resonant antennas. The highly confined electromagnetic field inbetween the tip end and antenna extremely amplifies the photoinduced force to the detectable level, while the excitation via plasmon internal reflection mode minimizes the environmental absorption. A polydimethylsiloxane (PDMS) layer (~1-2 nm thickness) functionalized on the AFM tip has been successfully identified in water with antennas of different sizes. Sampling volume of ~604 chemical bonds from PDMS was demonstrated with sub-10 nm spatial resolution confirmed by electric (E) field distribution mapping on antennas, which strongly suggests the desired requirements for interfacial spectroscopy. This platform demonstrates for the first time the application of photoinduced force microscopy in aqueous environments, providing a brand-new configuration to achieve highly enhanced nanoscale IR signals, which is extremely promising for future research of interfaces and nanosystems in aqueous environments.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Bo Chen
Yueguang Zhou
Peinian Huang
Chaochao Ye
Qian Cao
Yang Liu
Chanju Kim
Kresten Yvind
Jin Li
Chunhua Dong
Songnian Fu
Qiwen Zhan
Xuehua Wang
Minhao Pu
Jin Liu
摘要： The explorations of physical degrees of freedom with infinite dimensionalities, such as orbital angular momentum and frequency of light, have profoundly reshaped the landscape of modern optics with representative photonic functional devices including optical vortex emitters and frequency combs. In nanophotonics, whisper gallery mode microresonators naturally support orbital angular momentum of light and have been demonstrated as on-chip emitters of monochromatic optical vortices. On the other hand, whisper gallery mode microresonators serve as a highly-efficient nonlinear optical platform for producing light at different frequencies - i.e., microcombs. Here, we interlace the optical vortices and microcombs by demonstrating an optical vortex comb on an III-V integrated nonlinear microresonator. The angular-grating-dressed nonlinear microring simultaneously emits up to 50 orbital angular momentum modes that are each spectrally addressed to the frequency components ((longitudinal whispering gallery modes) of the generated microcomb. We further show that the integrated vortex comb with varied orbital angular momenta distributed across different frequencies exhibits unprecedented advantages in the synthesis of spatio-temporal optical pulses with time-varying orbital angular momenta. This work may immediately boost the development of integrated nonlinear/quantum photonics for exploring fundamental optical physics and advancing photonic quantum technology.
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