Fig. 4: Hybrid organic crystals as magnetically controllable organic crystal optical waveguides.

a, b Schematic of the experiments that demonstrate control over the shape of a crystal as optical waveguide by using magnetic field in two dimensions (a) and in three dimensions (b). The grey arrow represents the direction of movement of the magnet. c A crystal of MNP//4 acting as magnetically controllable optical waveguide. One end of the crystal was affixed to the base while the other was free and its position was controlled by moving the magnet. The crystal was excited by a 355 nm laser light (blue arrow). The yellow arrow indicates the direction of light propagation, and the white arrow shows the motion of the magnet and the tip of the crystal. The red dot is the light output. Note that the contrast in this figure has been enhanced for clarity of inspection of the light output. d–f Images of the crystal of 4 used as a waveguide in uncoated the straight state, 4 (d), coated straight state, MNP//4 (e) and coated bent state (f). g–i Fluorescence spectra collected at one tip of the crystal with different distances between the tip and the excitation site of the 355 nm light. The spectra in panels g, h and i correspond to the crystals shown in panels d, e and f, respectively.