Fig. 1. Experimental setup and material characterization. (a) Schematic diagram of optical tweezers system; (b) schematic diagram of chloroplast movement by optical tweezers; (c) schematic diagram of chloroplast stretching by optical tweezers; (d)--(f) micrographs of chloroplasts arranged by optical tweezers; (g) movement speed of chloroplast varying with optical power; (h) fluorescence image of chloroplasts, inset shows the leaves of Hydrilla verticillata; (i) three-dimensional confocal image of chloroplasts; (j) equivalent diameter distribution of chloroplasts; k) transmission spectrum of single chloroplast

Fig. 2. Light focusing by chloroplast microlenses with different shapes. (a)(b) Stretching process of chloroplasts; (c) A/B varying with stretching time; micrographs images of chloroplast(d)captured and (e) stretched by optical fiber tweezers; (f)(g) integration of optical fiber waveguide and chloroplast microlens; experimental images of light focusing by (h) spherical and (i) ellipsoidal chloroplast; simulated optical field distribution of light focusing by (j) spherical and (k) ellipsoidal chloroplast; (l) relationship among focal length of chloroplast, FWHM of chloroplast, and A/B, in which dots represent simulated data and solid lines represent fitted curces

Fig. 3. Light focusing characteristics of chloroplasts with different diameters. Focus of light with wavelength of 637 nm by chloroplasts with diameter of (a) 4.0 μm and (b) 9.0 μm; (c) focus of light with wavelength of 532 nm by chloroplast with diameter of 9.0 μm; (d)--(f) simulated optical field distributions of light focusing by chloroplasts corresponding to Figs. 3(a)--(c); (g) relationship among focal length of chloroplast, FWHM of chloroplast, and diameter of chloroplast, in which dots represent simulated data and solid lines represent fitted curces; (h) relationship among focal length of chloroplast, FWHM of chloroplast, and wavelength of incident light, in which dots represent simulated data and solid lines represent fitted curces

Fig. 4. Optical imaging and detection by chloroplast microlenses. (a1) SEM image of disk grating; images of gratings by (a2) spherical and (a3) ellipsoid chloroplast microlenses; (a4) actin filament strength distribution of Fig. 4(a3); (b1) schematic diagram of imaging of intracellular actin filaments by chloroplast; (b2)(b3) imaging process of actin filaments in plant cells by chloroplast microlenses; (b4) intensity distributions of plant actin filaments with and without chloroplasts; (c1) schematic diagram of fluorescence enhancement of quantum dots by chloroplasts; fluorescence enhancement of quantum dots by chloroplast microlenses with diameters of (c2) 4.5 μm and (c3) 9.0 μm; (c4) relationship diagram of fluorescence enhancement in Figs. 4(c2) and (c3); (d1) fluorescence image of quantum dots without chloroplasts; fluorescence enhancement of quantum dots by chloroplasts with A/B of (d2) 1.0 and (d3)1.5; (d4) relationship diagram of fluorescence enhancement in Figs. 4(d1)--(d3)

Fig. 5. Numerical simulation of fluorescence enhancement of quantum dots by chloroplast microlenses. (a1) optical field distribution diagram without microlens; fluorescence enhancement simulation of microlenses with diameter of (a2) 3.0 μm and (a3) 7.0 μm; (a4) fluorescence enhancement simulation of microlens with A/B=1.8; (b1)--(b4) polar coordinate diagrams corresponding to Figs. 5(a1)--(a4); (c) relationship among enhancement factor of chloroplast microlens, divergence angle of chloroplast microlens, and diameter, in which dots represent simulated data and solid lines represent fitted curces; (d) relationship among enhancement factor of chloroplast microlens, divergence angle of chloroplast microlens, and A/B, in which dots represent simulated data and solid lines represent fitted curces