Micropillar Cavities containing PMMA & Red-F Fluorescent Molecular Dye using Nb2O5/SiO2 DBRs

Photoluminescence emission from weakly coupled molecules has been investigated by placing a thin organic semiconductor film in one dimensional micropillar microcavities. The structure consisted of a Poly(methyl methacrylate) PMMA and red-emitting organic semiconductor (Red-F) thin film sandwiched between pair layers of dielectric mirrors made of materials that have low and high refractive indexes such as Nb2O5/SiO2 respectively. The structure's different diameter micropillars were designed using a focused ion beam. This construction is able to reserve the light in the micropillars in three directions due to total interior reflection horizontally and disseminated Bragg reflectors vertically. Optical emission properties such as changing the spectral wavelength of the released light depending on the micropillars diameter can be controlled. As a result, series of sharp lines of emission spectra were obtained from the micropillars with diameters staring from 4 μm to 10 μm. By placing a 200 nm of thin film using (Red-F & PMMA) polymers into a 7 μm diameter micropillar, a quality factor of 446.1 was obtained. Besides, it was also obvious that as the micropillar diameter was decreased, the energy of all cavity modes gradually blue-shifted.