Self-assembly three-dimensional optical devices: from microsphere to microlens array.

We report rapid formation of three-dimensional micro optical devices by silica nanoparticle self-assembly in a face-centered cubic (fcc) structure. By controlling the hydrophobic interactions, the self-assembled products are fabricated into different morphologies, which include microsphere and hemisphere. These structures have specific applications in microsphere resonant cavities and microlens arrays. The whispering gallery mode of the formed microsphere is excited by the tapered fiber to demonstrate the optical characters of the microsphere. Moreover, the properties of the fabricated microlens and microlens array are tested through insertion in an imaging system. Ultimately, the optical devices with advanced functions are demonstrated by the secondary phase infiltrating into the interstitial space of silica nanoparticles. This report will open a new direction in manufacturing multifunctional and miniature optical devices by an ultrasimple self-assembly approach.