分类： 光学 >> 量子光学 提交时间： 2023-02-19
Jingnan Yang
Shushu Shi
Xin Xie
Shiyao Wu
Shan Xiao
Feilong Song
Jianchen Dang
Sibai Sun
Longlong Yang
Yunuan Wang
Zi-Yong Ge
Bei-Bei Li
Zhanchun Zuo
Kuijuan Jin
Xiulai Xu
摘要： We report on controllable cavity modes through controlling the backscattering by two identical scatterers. Periodic changes of the backscattering coupling between two degenerate cavity modes are observed with the angle between two scatterers and elucidated by a theoretical model using two-mode approximation and numerical simulations. The periodically appearing single-peak cavity modes indicate mode degeneracy at diabolical points. Then interactions between single quantum dots and cavity modes are investigated. Enhanced emission of a quantum dot with a six-fold intensity increase is obtained in a microdisk at a diabolical point. This method to control cavity modes allows large-scale integration, high reproducibility and fexible design of the size, location, quantity and shape for scatterers, which can be applied for integrated photonic structures with scatterer-modified light-matter interaction.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yanwu Liu
Chenghao Lao
Min Wang
Yinke Cheng
Shiyao Fu
Chunqing Gao
Jianwei Wang
Bei-Bei Li
Qihuang Gong
Yun-Feng Xiao
Wenjing Liu
Qi-Fan Yang
摘要： The frequency and orbital angular momentum (OAM) are independent physical properties of light that both offer unbounded degrees of freedom. However, creating, processing, and detecting high-dimensional OAM states have been a pivot and long-lasting task, as the complexity of the required optical systems scales up drastically with the OAM dimension. On the other hand, mature toolboxes -- such as optical frequency combs -- have been developed in the frequency domain for parallel measurements with excellent fidelity. Here we correlate the two dimensions into an equidistant comb structure on a photonic chip. Dissipative optical solitons formed in a nonlinear microresonator are emitted through the engraved angular gratings with each comb line carrying distinct OAM. Such one-to-one correspondence between the OAM and frequencies manifests state-of-the-art extinction ratios over 18.5 dB, enabling precision spectroscopy of optical vortices. The demonstrated vortex soliton microcombs provide coherent light sources that are multiplexed in the spatial and frequency domain, having the potential to establish a new modus operandi of high-dimensional structured light.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Whispering gallery mode (WGM) microcavities have been widely used for high-sensitivity ultrasound detection, due to their optical and mechanical resonances enhanced sensitivity. The ultrasound sensitivity of the cavity optomechanical system is fundamentally limited by the thermal noise. In this work, we theoretically and experimentally investigate the thermal-noise-limited sensitivity of a WGM microdisk ultrasound sensor, and optimize the sensitivity by varying the radius and thickness of the microdisk, as well as using a trench structure around the disk. Using a microdisk with a radius of 300 um and thickness of 2 um, a peak sensitivity of 1.18 uPa Hz^{-1/2} is achieved at 82.6 kHz, which is to our knowledge the record sensitivity among the cavity optomechanical ultrasound sensors. Such high sensitivity can improve the detection range of air-coupled ultrasound sensing technology.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Xin Xie
Sai Yan
Jianchen Dang
Jingnan Yang
Shan Xiao
Yunuan Wang
Shushu Shi
Longlong Yang
Danjie Dai
Yu Yuan
Nan Luo
Ting Cui
Gaohong Chi
Zhanchun Zuo
Bei-Bei Li
Can Wang
Xiulai Xu
摘要： Slow light in topological valley photonic crystal structures offers new possibilities to enhance light-matter interaction. We report a topological cavity based on slow light topological edge mode for broadband Purcell enhancement. The topological edge modes with large group indices over 100 can be realized with a bearded interface between two topologically distinct valley photonic crystals, featuring the greatly enhanced Purcell factor because of the increased local density of states. In the slow light regime, the topological cavity supports much more cavity modes with higher quality factor than that in the fast light regime, which is both demonstrated theoretically and experimentally. We demonstrate the cavity enables the broadband Purcell enhancement together with substantial Purcell factor, benefiting from dense cavity modes with high quality factor in a wide spectral range. It has great benefit to the realization of high-efficiency quantum-dot-based single-photon sources and entangled-photon sources with less restriction on spectral match. Such topological cavity could serve as a significant building block toward the development of photonic integrated circuits with embedded quantum emitters.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Hao Yang
Zhi-Gang Hu
Yuechen Lei
Xuening Cao
Min Wang
Jialve Sun
Changhui Li
Zhanchun Zuo
Xiulai Xu
Bei-Bei Li
摘要： Owing to their dual-resonance enhanced sensitivity, cavity optomechanical systems provide an ideal platform for ultrasound sensing. In this work, we realize high sensitivity air-coupled ultrasound sensing from kilohertz (kHz) to megahertz (MHz) frequency range based on whispering gallery mode microcavities. Using a 57 um-diameter microtoroid with high optical Q factor (~10^7) and mechanical Q factor (~700), we achieve sensitivities of 46 uPa Hz^{-1/2}-10 mPa Hz^{-1/2} in a frequency range of 0.25-3.2 MHz. Thermal-noise-limited sensitivity is realized around the mechanical resonance at 2.56 MHz, in a frequency range of 0.6 MHz. We also observe the second- and third-order mechanical sidebands, and quantitatively study the intensities of each mechanical sideband as a function of the mechanical displacement. Measuring the combination of signal to noise ratios at all sidebands has the potential to extend the dynamic range of ultrasound sensing. In addition, to improve the ultrasound sensitivity in the kHz frequency range, we use a microdisk with a diameter of 200 um, and achieve sensitivities of 1.83 uPa Hz^{-1/2}-10.4 mPa Hz^{-1/2} in 30 kHz-1.65 MHz range.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Fully reconfigurable add-drop filters (ADFs) have important applications in optical communication and information processing. Here we demonstrate a broadly tunable add-drop filter based on a double-disk cavity optomechanical system, side-coupled with a pair of tapered fiber waveguides. By varying the coupling rates between the cavity and the two waveguides, we investigate the dependence of the through (drop) efficiency on the coupling rates, which agrees well with the theoretical results. By optimizing the cavity-waveguide coupling rates, a drop efficiency of 89% and a transmission of 1.9% have been achieved. Benefiting from the large optomechanical coupling coefficient of the double-disk microcavity, a tuning range of 8 nm has been realized, which is more than one free spectral range (FSR) of the cavity. This is realized by changing the air gap of the double disk using a fiber tip, which is controlled by a piezoelectrical nanostage, with a required voltage of 7 V. As a result, both the through and drop signals can be resonant with any wavelength within the transparent window of the cavity material, which indicates that the ADF is fully reconfigurable.
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