Controlling aspect ratios of suspended nanorods fabricated by multi-photon polymerization

Nanorods are building blocks of three-dimensional photonic crystals and other nanostructures fabricated by multi-photon polymerization with femtosecond laser pulses. The aspect ratios of their cross sections are critical to the in-plane and the interlayer rod distances, which greatly affect the performance. Here we demonstrate the control of aspect ratios from ∼3 to 0.85. At a high scanning speed, aspect ratios can be smaller than unity with a lateral size of ∼150 nm. The results indicate that cylindrical nanorods can be polymerized by the commonly used transverse scanning method to improve the qualities of three-dimensional nanostructures.