Exciton-polaritons
in 2D lattice geometries now attract considerable attention as systems
in which to explore new physics. However, such structures are relatively
difficult to fabricate as this can involve sophisticated milling or
etching of cavity layers to create arrays of defects. Here, a straightforward
technique is reported that allows rapid fabrication of 2D polariton
lattices that operate at room temperature. Specifically, laser patterning
has been used to write a 2D square lattice of defects into a sacrificial
polymer layer. An organic microcavity structure is then built on top
of the patterned polymer, with the morphology of the patterned polymer
propagating through the subsequent layers and spatially modifying
the optical path length of the active cavity region. Using real- and
momentum-space spectroscopy, the formation of gapped polaritonic band
structures has been demonstrated at room temperature. The optical
writing approach discussed here opens up the way for fabrication of
more complex 2D-lattice geometries for studying topological physics
at room temperature.
Organic semiconductors are a promising platform for ambient polaritonics. Several applications, such as polariton routers, and many-body condensed matter phenomena are currently hindered due to the ultra-short polariton lifetimes in organics. Here, we employ a single-shot dispersion imaging technique, using 4 nanosecond long non-resonant excitation pulses, to study polariton lasing in a λ /2 planar organic microcavity filled with BODIPY-Br dye molecules. At a power threshold density of 1.5MW /cm 2 , we observe the transition to a quasi-steady state, 1.2 ns long-lived, single-mode polariton lasing and the concomitant superlinear increase of photoluminescence, spectral line-narrowing, and energy blueshift.
We have developed a simplified approach to fabricate high-reflectivity mirrors suitable for applications in a strongly-coupled organic-semiconductor microcavity. Such mirrors are based on a small number of quarter-wave dielectric pairs deposited on top of a thick silver film that combine high reflectivity and broad reflectivity bandwidth. Using this approach, we construct a microcavity containing the molecular dye BODIPY-Br in which the bottom cavity mirror is composed of a silver layer coated by a SiO2 and a Nb2O5 film, and show that this cavity undergoes polariton condensation at a similar threshold to that of a control cavity whose bottom mirror consists of ten quarter-wave dielectric pairs. We observe, however, that the roughness of the hybrid mirror—caused by limited adhesion between the silver and the dielectric pair—apparently prevents complete collapse of the population to the ground polariton state above the condensation threshold.
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