An ultrathin nonlinear optical (NLO) organic surface composed of numerous self-assembled frustum-shaped whispering-gallery-mode resonators displays both two-photon luminescence and second-harmonic-generation signals. A super-second-order increase of the NLO intensity with respect to pump power confirms the microlasing action and practical usefulness of the NLO organic surfaces.

resonators, and nano-antennas. [7][8][9][10][11][12][13] In addition to these structures, their organic equivalent can be a fascinating alternative. Additionally, observing this weak chiral event in the (usually feeble) NLO (nonlinear optical) signal is a challenging endeavor. In this context, we wondered about the possibility of using organic micro-optical waveguides [14][15][16][17] to produce and guide chirality-controlled NLO signals as these structures are known to confine photons in two dimensions and allow 1D propagation. Though a few NLO waveguides are reported, [18][19][20][21][22][23][24][25] to the best of our knowledge, we are not able to access any reports on organic waveguides exhibiting chirality effect in the NLO signal. To fabricate nano/microcrystalline [25,26] chiral waveguides, we envisioned organic molecules possessing chirality and electron donor-acceptor characters. [26,27] Generally, electron push-pull organic molecules due to their large dipole moment provide large Frenkel exciton binding energy (up to 1 eV), [1,27] high photoluminescence (PL) efficiency, [26,27] tunable optical band gap, [1,25,26] easy solution processability, [1] size and shape control of nanostructures, [14,29,30] and more importantly, easy access to generate chirality information encoded NLO signals [12] such as multiphoton PL [12,21,28] and second-harmonic generation (SHG). [13] The latter signal arises as a result of the nonzero second-order electric susceptibility (χ (2) ≠ 0) emerging from the non-centrosymmetric crystal packing provided by the molecular chirality.For our investigations, we chose enantiomeric R-and S-4,4′-(2,2′-diethoxy-1,1′-binaphthyl-6,6′-diyl)-dibenzaldehyde (1-R and 1-S) molecules [12] (Figure 1A). The molecular structures of 1-R and 1-S possess: i) chirality, which emerges from their axially chiral nature of the molecule provided by the chiral π-conjugated spacer, ii) abilities to crystallize in chiral non-centrosymmetric crystallographic space group, iii) multiphoton absorbance and SHG as a result of charge-transfer (CT) character provided by the electron donating ethoxy and electron accepting benzaldehyde functional groups attached to enantiomers, and iv) CD effect in the NLO signal due to chiral nature of the molecules.Here in this work, we report the first realization of multiphoton pumped organic chiral micro-rod waveguides self-assembled from 1-R and 1-S enantiomers displaying chiro-NLO effects. These enantiomeric micro-rods generate one-, two-, three-photon pumped PL including SHG and self-guide Production of chiral light and its manipulation down to nanolevel is a very challenging endeavor in the area of nanophotonics. In this work, the above demanding requirements are realized explicitly in two R-and S-type chiral organic optical waveguides which are self-assembled from charge-transfer type axially chiral enantiomeric molecules. These enantiomerically pure micro-optical waveguides generate one-, two-, three-photon pumped optical emissions. Remarkably, these waveguides also demonstrate...

Enantiomeric R and S type organic whispering-gallery-mode (WGM) optical micro-cavities display an enhanced CD-NLO effect due to increased light–matter interaction.