Self-assembled organic hexagonal micro-prisms with high second harmonic generation efficiency for photonic devices.

Multiwavelength coherent light sources are key components for circuit integration of nanophotonics. Here, we demonstrated highly efficient second harmonic generation (SHG) in single-crystalline hexagonal micro-prisms (HMPs) of 3-methyl-4-methoxy-4'-nitrostilbene (MMONS) prepared via a facile self-assembled method. We found that the SHG conversion efficiency (ηSHG) of MMONS HMPs increases with increasing the prism side length (d). Local electric field |E|(2) calculations suggest that the symmetrical hexagonal prism shape of HMPs supports helically propagating modes. The SHG light produced at one end of HMP can be coupled into whispering-gallery (WG) like optical modes with a coupling efficiency of 50-80% and helically propagates along the length of HMPs toward another end. Based on this unique helical propagation of SHG light, we construct an optical interconnector by placing a single MMONS HMP on the top of a single micro-ribbon of 1,2-diphenyl-2-pyrazoline (DP). These easily fabricated MMONS HMPs can act as a coherent source, which adds a key component to the tool box of organic nano- and micro-structure optoelectronics.