A new publication from Opto-Electronic Advances; DOI 10.29026/oea.2022.210026 overviews ultrafast multi-target control of tightly focused light fields.
Space-time shaping of ultrafast pulse laser is considered as a powerful tool for the development of high-efficiency laser trapping, ultrafast optical spanner, precise time-resolution measurement, ultrafast spectroscopy, integrated optical chip and high-resolution imaging. In this regard, numerous research efforts have been devoted to achieve the specific spatial modulation and temporal encoding of light fields. These works, however, focus primarily on the single-functional space-time shaping of light fields and fully overlook the variation details of light fields within an ultrashort time regime. Thus, how to realize the ultrafast multi-target control of light fields by combining the vector-vortex (spatial) traits with the ultrafast time (temporal) variations remains to be elusive until now, which hinders not only instructive insights into the ultrafast light-matter interactions but also the applications in the novel optical tweezer settings.
Researchers led by Professor Baohua Jia at Swinburne University of Technology, Australia, and Dr. Zhongquan Nie at Taiyuan University of Technology, presented a new concept for realizing ultrafast modulation of multi-target focal fields based on the facile combination of the time-dependent vectorial diffraction theory with the fast Fourier transform. It is achieved by tightly focusing radially polarized femtosecond pulse vortex laser beams in a single objective lens geometry, as shown in Fig. 1. It is uncovered that the ultrafast temporal degree of freedom within a configurable temporal duration (~400 fs) plays a pivotal role in determining the rich and exotic features of the focused light field at one time, namely, bright-dark alternation, periodic rotation, and longitudinal/transverse polarization conversion. The underlying control mechanisms have been in turn unveiled by the creation of zero or π phase variation, time-dependent Gouy phase shift, and energy flux redistribution, as showcased in Fig. 2. Additionally, the initially experimental results demonstrated by this work are well in agreement with their proposed theoretical predictions and numerical analyses, as demonstrated in Fig. 3.
The advantages of this work lie in not only enabling high-efficiency operation and low-complexity design of optical setup, but allow increasing the controllable temporal degree of freedom into the practical optical tweezer strategies compared with that of traditional approaches. More importantly, the routes presented is capable to simultaneously achieve multiple and controllable targets of light fields in a single geometry configuration. Besides being of academic interest in diverse ultrafast spectral regimes, these peculiar behaviors of the space-time evolutionary beams promise to underpin prolific ultrafast-related applications such as multifunctional integrated optical chip, high-efficiency laser trapping, microstructure rotation, super-resolution optical microscopy, precise optical measurement, and liveness tracking.
Article reference: Zhang YX, Liu XF, Lin H, Wang D, Cao ES et al. Ultrafast multi-target control of tightly focused light fields. Opto-Electron Adv 5, 210026 (2022). doi: 10.29026/oea.2022.210026
Keywords: ultrafast optical field / vectorial diffraction theory / fast Fourier transform / vectorial vortex beam / space-time shaping
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The Centre for Translational Atomaterials (CTAM) led by Professor Baohua Jia is a Research Centre at Swinburne University of Technology, Victoria, Australia, focuses on fundamental research of atomic material (Atomaterials) design, engineering as well as the development of transformative technologies of such novel materials. The CTAM is the world first dedicated Centre on Atomaterial research and translation. There are 70 research staffs and students involved in the CTAM. The research covers intelligent atomic structure design and synthesis, in-situ characterization, functional device design and fabrication, structure design and optimization as well as device engineering and translation.
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Opto-Electronic Advances (OEA) is a high-impact, open access, peer reviewed monthly SCI journal with an impact factor of 9.682 (Journals Citation Reports for IF 2020). Since its launch in March 2018, OEA has been indexed in SCI, EI, DOAJ, Scopus, CA and ICI databases over the time and expanded its Editorial Board to 36 members from 17 countries and regions (average h-index 49).
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