Author Affiliations
1University of Chinese Academy of Sciences, Hangzhou Institute for Advanced Study, College of Physics and Optoelectronic Engineering, Hangzhou, China2Westlake University, School of Engineering, Key Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang Province, Hangzhou, China3Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, Chinashow less
Fig. 1. Optical and thermal properties of hybrid
plate–silica microfiber systems. (a) Sketch of a
plate on top of a suspended microfiber. Zoomed inset: a
plate is modeled as a dielectric bulk slab sandwiched between two metallic thin layers. (b) Micro-Raman spectrum of a
plate measured by a 532-nm pumping laser. Inset: confocal laser scanning microscopy image of a mechanical-exfoliated
plate on a
substrate. (c) Simulated absorption spectrum of a hybrid
plate–microfiber system under incidence of fundamental
mode of the microfiber. (d) Simulated modal profiles of the
mode without (left panel) and with (right panel) the
plate. The arrows specify the directions of modal electric fields. (e) Simulated characteristic temperature distributions in the central
plane of
and gold plates at
, 100, 1000 ns when heated by pulsed light. In (c)–(e), the microfiber has a radius of
and a refractive index of 1.45. The
plate has a width of
, a length of
, and a thickness of 300 nm, and its surface and bulk refractive indices are adopted from Ref.
29. The Au plate has the same geometrical parameters as the
plate. The details of the thermal simulations in (e) are given in Note S1 in the
Supplementary Material.
Fig. 2. Experimental observations of a plate moving spirally around a microfiber. (a) Sketch of experimental setup implemented in a vacuum chamber. VOA, variable optical attenuator; FC, fiber coupler; MF, microfiber; and PM, power meter. (b) Temporal sequencing SEM images of a plate moving around a microfiber. The microfiber has a diameter of . The supercontinuum laser pulses have 2.6-ns duration, 230-Hz repetition rate, 0.1-mW average power, and wavelength range from 450 to 2400 nm. Scale bar: (Video 1, MP4, 4.34 MB [URL: https://doi.org/10.1117/1.APN.1.2.026005.s1). (c) Fourier transformation of the detected areas of the plate during the motion. The spectral peak specifies the azimuthal rotation frequency of the plate. The axis is linear and the shaded region here is to better show its rotation frequency. (d) Translation displacement of the plate along the axial direction of the microfiber as a function of time.
Fig. 3. Manipulating motion speed of plates by tuning repetition rates of laser pulses. Note that the integrated single-pulse energy remains the same as the repetition rate changes. Scale bars: (Video 2, MP4, 19.6 MB [URL: https://doi.org/10.1117/1.APN.1.2.026005.s2]).
Fig. 4. Stable motion of a plate degenerates into unstable motion by thermal effects. Sequencing SEM images show (a) stable and (b) unstable motions with pulse repetition rates of 2.2 kHz and 4.8 kHz, respectively. Scale bars: (Video 3, MP4, 9.73 MB [URL: https://doi.org/10.1117/1.APN.1.2.026005.s3]).
Fig. 5. SEM images of a plate (a) before and (b) after motion. The red and white dashed circles in (b) mark formed microbumps and a myriad of small spheres, respectively.
Fig. 6. Liquid-like motion of plates on microfibers. (a) Time sequencing SEM images of a plate showing liquid-like motion. The used supercontinuum laser pulse has 5.4-mW average power and 11.5-kHz repetition rate. A large microbump contacting with the microfiber and a small one is marked with a rectangle and circle, respectively (Video 4, MP4, 895 kB [URL: https://doi.org/10.1117/1.APN.1.2.026005.s4]). (b) Zoomed-in microbump [corresponding to the marked rectangle in (a)] showing asymmetric contact angles. Scale bar: . (c) Horizontal and (d) vertical displacements of the point in the plate as functions of time. The point is labeled in (a). (e) Two exemplified samples show that horizontal motion direction of the plates points from a small microbump close to the microfiber (marked with circle) to a large one contacting with the microfiber (marked with rectangle). Scale bars: (Video 5, MP4, 7.90 MB [URL: https://doi.org/10.1117/1.APN.1.2.026005.s5]).