Dimension Engineering of Stimuli‐Responsive 1D Molecular Crystals into Unusual 2D and 3D Zigzag Waveguides

We demonstrate an innovative technique to achieve organic 2D and 3D waveguides with peculiar shapes from an acicular, stimuli‐responsive molecular crystal, (2 Z ,2′ Z )‐3,3′‐(anthracene‐9,10‐diyl)bis(2‐(3,5‐bis(trifluoromethyl)phenylacrylonitrile), Ant‐CF 3 . The greenish‐yellow fluorescent (FL) Ant‐CF 3 molecular crystals exhibit laser power‐dependent permanent mechanical bending in 2D and 3D. Investigation of a single‐crystal using spatially‐resolved Raman/FL/electron microscopy, and theoretical calculations revealed photothermal ( Z , E )/( E , E ) isomerization‐assisted transition from crystalline to amorphous phase at the laser‐exposed regions. This phenomenon facilitates the dimension engineering of a 1D crystal waveguide into 2D waveguide on a substrate or a 3D waveguide in free space. The bends can be used as interconnection points to couple different optical elements. The presented technique has broader implications in organic photonics and other crystal‐related photonic technologies.