分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The escape phenomenon, mainly caused by thermal effects, is known as an obstacle to the further practical application of optical levitation system in vacuum. Irregular photophoresis induced by thermal effects can act as an amplifier of Brownian motion. Studies on this topic provide interpretation for particle escaping phenomenon during the pressure decreasing process, as well as valuable insights into the micro- and nanoscale thermal effects in optical trap in vacuum. In this paper, we derive and test a dynamic model for the motion of an optically levitated particle in a non-equilibrium state and demonstrate the escaping mechanism of heated particles. The result of theoretical investigations is consistent with experimental escape at 0.1mbar. This work reveals and provides a theoretical basis for the stable operation of laser levitated oscillator in high vacuum and pave the way for the practicability of ultra-sensitive sensing devices.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Oscillators based on levitated particles are promising for the development of ultrasensitive force detectors. The theoretical performance of levitated nanomechanical sensors is usually characterized by the so-called thermal noise limit force detection sensitivity, which does not exhibit spectral specificity in practical measurements. To characterize the actual detection performance, we propose a method for the force detection sensitivity calibration of a levitated nanomechanical sensor based on the harmonic Coulomb force. Utilizing the measured transfer function, we obtained the force detection sensitivity spectrum from the position spectrum. Although the thermal noise limit force detection sensitivity of the system reached $\rm\left( {4.39 \pm 0.62} \right) \times {10^{ - 20}} N/H{z^{1/2}}$ at $\rm{2.4\times10^{-6} mbar}$ with feedback cooling, the measured sensitivity away from the resonance was of the order of $\rm10^{-17} N/Hz^{1/2}$ based on the existing detection noise level. The calibration method established in our study is applicable to the performance evaluation of any optical levitation system for high-sensitivity force measurements.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Nanomechanical resonator based on levitated particle exhibits unique advantages in the development of ultrasensitive electric field detector. We demonstrate a three-dimensional, high-sensitivity electric field measurement technology using the optically levitated nanoparticle with a known net charge. By changing the relative position between nanoparticle and parallel electrodes, the three-dimensional electric field distribution is scanned. The measured noise equivalent electric intensity with charge amount of 100 reaches the order of {\rm{1\mu V/cm/H}}{{\rm{z}}^{{\rm{1/2}}}} at 1.4 \times {10^{ - 7}}mbar. Linearity analysis near resonance frequency shows a measured linear range over 91dB limited only by the maximum output voltage of the driving equipment. This work may provide avenue for developing a high-sensitive electric field sensor based on optically levitated nano-resonator.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In recent years, levitated particles of optical traps in vacuum have shown enormous potential in precision sensor development and searching for new physics. The accuracy of the calibration relating the detected signal to absolute displacement of the trapped particle is a critical factor for absolute measurement performance. In this paper, we suggest and experimentally demonstrate a novel calibration method for optical tweezers based on free-falling particles in vacuum, where the gravitational acceleration is introduced as an absolute reference. Our work provides a calibration protocol with great certainty and traceability, which is significant in improving the accuracy of precision sensing based on optically levitated particles.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Weiru Fan
Tianrun Chen
Xingqi Xu
Ziyang Chen
Huizhu Hu
Delong Zhang
Da-Wei Wang
Jixiong Pu
Shi-Yao Zhu
摘要： Optical phase contains key information for biomedical and astronomical imaging. However, it is often obscured by layers of heterogeneous and scattering media, which render optical phase imaging at different depths an utmost challenge. Limited by the memory effect, current methods for phase imaging in strong scattering media are inapplicable to retrieving phases at different depths. To address this challenge, we developed a speckle three-dimensional reconstruction network (STRN) to recognize phase objects behind scattering media, which circumvents the limitations of memory effect. From the single-shot, reference-free and scanning-free speckle pattern input, STRN distinguishes depth-resolving quantitative phase information with high fidelity. Our results promise broad applications in biomedical tomography and endoscopy.
点击量
待评议
点击量
下载量
评论
