Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and t...Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps,however, the underlying physical mechanism is mainly confined within the SA regime because thresholdvalues required to excite the RSA regime are extremely high. Herein, we demonstrate, both in theory andexperiment, nonlinear optical tweezing within the RSA regime, proving that a fascinating composite trappingstate is achievable at ultrahigh intensities through an optical force reversal induced through nonlinearabsorption. Integrated results help in perfecting the nonlinear optical trapping system, thereby providingbeneficial guidance for wider applications of nonlinear optics.展开更多
The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, althoug...The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam(APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity.This research introduces new methods for the flexible control of polarization singularities in tightly focused fields,thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing.These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.展开更多
基金This work was supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2020B0301030009)the National Natural Science Foundation of China(Grant Nos.61975128,61935013,and 62175157)+3 种基金the Shenzhen Science and Technology Program(Grant Nos.JCYJ20210324120403011 and RCJC20210609103232046)the Natural Science Foundation of Guangdong Province(Grant No.2019TQ05X750)the Key Research Project of Zhejiang Lab(Grant No.2022MG0AC05)thre Shenzhen Peacock Plan(Grant No.KQTD20170330110444030)。
文摘Nonlinear responses of nanoparticles induce enlightening phenomena in optical tweezers. With thegradual increase in optical intensity, effects from saturable absorption (SA) and reverse SA (RSA) arise insequence and thereby modulate the nonlinear properties of materials. In current nonlinear optical traps,however, the underlying physical mechanism is mainly confined within the SA regime because thresholdvalues required to excite the RSA regime are extremely high. Herein, we demonstrate, both in theory andexperiment, nonlinear optical tweezing within the RSA regime, proving that a fascinating composite trappingstate is achievable at ultrahigh intensities through an optical force reversal induced through nonlinearabsorption. Integrated results help in perfecting the nonlinear optical trapping system, thereby providingbeneficial guidance for wider applications of nonlinear optics.
基金Guangdong Major Project of Basic and Applied Basic Research (2020B0301030009)National Natural Science Foundation of China (62375177,62175157, 12304330, 92250304, 92150301)+3 种基金Shenzhen Science and Technology Program (JCYJ20210324120403011,RCJC20210609103232046)Shenzhen Peacock Plan(KQTD20170330110444030)China Postdoctoral Science Foundation (2022M722906)Natural Science Foundation of Zhejiang Province (LQ24F050014)。
文摘The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam(APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity.This research introduces new methods for the flexible control of polarization singularities in tightly focused fields,thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing.These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.