M. Scott Bradley

Highly efficient resonant coupling of optical excitations in hybrid organic/inorganic semiconductor nanostructures

The integration of organic and inorganic semiconductors on the nanoscale offers the possibility of developing new photonic devices that combine the best features of these two distinct classes of material. Such devices could, for example, benefit from the large oscillator strengths found in organic materials and the nonlinear optical properties of inorganic species. Here we describe a novel hybrid organic/inorganic nanocomposite in which alternating monolayers of J-aggregates of cyanine dye and crystalline semiconductor quantum dots are grown by a layer-by-layer self-assembly technique. We demonstrate near-field photon-mediated coupling of vastly dissimilar optical excitations in the two materials that can reach efficiencies of up to 98% at room temperature. By varying the size of the quantum dots and thus tuning their optical resonance for absorption and emission, we also show how the ability of J-aggregates to harvest light can be harnessed to increase the effective absorption cross section of the quantum dots by up to a factor of ten. Combining organic and inorganic semiconductors in this way could lead to novel nanoscale designs for light-emitting, photovoltaic and sensor applications.

Critically coupled resonators in vertical geometry using a planar mirror and a 5 nm thick absorbing film

A (5.1+/-0.5) nm thick film of high oscillator strength J-aggregated dye critically couples to a single dielectric mirror, absorbing more than 97% of incident lambda = 591 nm wavelength light, corresponding to an effective absorption coefficient of (6.9+/-0.7) x 10(6) cm(-1) for (film thickness)/lambda < 1%.

Micron-Scale Molecular Organic Microcavity Arrays Patterned With Thin-Film Contact-Patterning

We demonstrate arrays of molecular organic thin film microcavities with 5 μm lateral features fabricated by thin-film contact-patterning using polydimethylsiloxane stamps. The contact-patterning method enables engineering of shifts in the microcavity resonance energy across the microcavity array. Small resonance shifts are imparted by patterning thickness of organic films in multilayer structures, and large resonance shifts are formed by patterning thick films. The contact-patterning method is scalable, extendable to patterning sub-micronmeter organic photonic device features.

Exciton-polaritons at room temperature in dielectric microcavities exhibiting rabi-splitting Ω R ≫ 100 meV

Exciton-Polariton states are observed at room temperature in planar sputter-coated dielectric microcavities containing 5 nm thick film of J-aggregated dye as excitonic layer exhibiting Rabi-splitting Ω_R ≫ 100meV and empty cavity Q factor ≫> 700.

Critically coupling a 5.1 nm thick J-aggregate layer to a single dielectric mirror, resulting in an effective peak absorption constant of 6.9 x 10 6 cm −1

A 5.1 nm thick film of high oscillator strength J-aggregated dye, which gives rise to strong optical coupling, critically couples to a single dielectric mirror, absorbing 97% of incident light (effective absorption coefficient of 6.9 times 106 cm-1).