Spatially Dependent Optical Transmissivity of High Aspect Ratio Shape Memory Polymer Micropost Arrays with Tunable Angle

Authors：Xu, Yuanhao; Leung, Cheuk Wai; Pang, Stella W.^*

Source：Advanced Materials Technologies, 2023.

DOI：10.1002/admt.202300847

• beam splitting
• controlled micropost bending
• depolarization
• dynamic shape recovery
• imprinting
• shape memory polymer

Shape memory polymer (SMP) is a smart material that can memorize a permanent shape and, when exposed to a certain stimulus, recovers its original shape from a programmed temporary shape. High aspect-ratio microposts are fabricated using deep reactive-ion etching and thermal imprint, and are mechanically deformed to temporary bent morphologies. By applying a temperature gradient across this array of bent SMP microposts, they gradually recover at different speed to their original vertical position, starting from the heated end, resulting in a spatial dependence of bending recovery. The gradual recovery phenomenon is employed to illustrate the spatially dependent optical transmissivity of the micropost array, which exhibit different micropost angles. These findings provide evidence for the manipulation of optical transmission characteristics, encompassing diffraction, waveguiding, and depolarization, across various orientations. This high aspect ratio SMP micropost array is potentially useful for various optical devices and applications. @@@ High aspect ratio shape memory polymer microposts are fabricated with precise spatial control, ranging from 20 degrees to 90 degrees in micropost angle. They control the optical power distributions of a laser beam split by the micropost array, depending on different bending angles. Additionally, the study demonstrates a dependency of laser polarization on micropost bending direction and angle.image