Enabling enhanced emission and low-threshold lasing of organic molecules using special Fano resonances of macroscopic photonic crystals

Abstract

The nature of light interaction with matter can be dramatically altered in optical cavities, often inducing nonclassical behavior. In solid-state systems, excitons need to be spatially incorporated within nanostructured cavities to achieve such behavior. Although fascinating phenomena have been observed with inorganic nanostructures, the incorporation of organic molecules into the typically inorganic cavity is more challenging. Here, we present a unique optofluidic platform comprising organic molecules in solution suspended on a photonic crystal surface, which supports macroscopic Fano resonances and allows strong and tunable interactions with the molecules anywhere along the surface. We develop a theoretical framework of this system and present a rigorous comparison with experimental measurements, showing dramatic spectral and angular enhancement of emission. We then demonstrate that these enhancement mechanisms enable lasing of only a 100-nm thin layer of diluted solution of organic molecules with substantially reduced threshold intensity, which has important implications for organic light-emitting devices and molecular sensing.fluorescence enhancement | enhanced light-matter interaction O rganic molecules are pervasive in daily life: from natural proteins, to human synthesized fluorescing labels, to organic semiconductors. The interaction of light with such molecules is at the heart of important technological advances in biomolecular detection (1-4), fluorescent microscopy (5), and organic light-emitting devices (6-9), as well as more fundamental studies of cavity quantum electrodynamics (10-12) and various types of enhanced spectroscopy (13) and sensing (14). In all, it is frequently sought to alter (15-18) and often to enhance this interaction by allowing it to occur in a typically nanostructured cavity, where both the lifetime of the resonances and the optical density of states (DOS) (19) can be tailored. However, there are inherent challenges in incorporating organic molecules in such cavities: first, their dissimilar compositional structure makes it difficult to incorporate them within the highdielectric regions of the cavity, where long-lifetime resonances concentrate their electromagnetic energy. Second, micro-and nanostructured cavities typically only have a small portion of their mode volumes extending outside their high-dielectric regions, making it challenging to bring external entities precisely to within that volume. Third, patterning of organic materials at the nanoscale is extremely challenging and incompatible with inorganic processes. As a result, experimental realizations of systems of excitons of organic molecules and optical resonances are limited compared with systems of inorganic quantum nanostructures.Here, we present and study a unique dielectric surface that enables simple incorporation of organic molecules onto a macroscopic nanostructured resonant cavity. This system demonstrates strongly enhanced interaction of light with organic molecules that are brought to within 100 nm of its m...

Direct imaging of isofrequency contours in photonic structures

“…However, reflection measurements require constantly moving the spectrometer to maintain overlap with the specularly reflected beam. On the other hand, enhanced fluorescence measurements require additional incorporation of emitters and are limited by their emission bandwidth ( 48 ). Finally, enhanced absorption measurements inevitably lower the quality factors of the resonances because of the incorporation of a lossy medium ( 49 ).…”

Quasi‐Continuous‐Wave Organic Thin‐Film Distributed Feedback Laser

“…[ 36 ] In general, E th and the laser gain are inversely proportion to Φ PL . [ 37,38 ] Our devices were operated in the quasi-cw mode using optical pulses with a wavelength of 365 nm and a width of 10 ps from a Ti-sapphire laser. Figure 3 shows the streak camera images of laser oscillations and corresponding temporal changes of laser intensities in the BSBCz:CBP blend fi lm at the lasing wavelength.…”

Optofluidic lasers with a single molecular layer of gain

“…1–5 It has a broad range of applications in novel photonic devices, such as on-chip tunable coherent light source 6–10 and bio-controlled laser, 11–16 and in sensitively analyzing biomolecules. 2,3,5,17–22 The optofluidic laser exhibits great versatility.…”

“…Various microcavities have been developed, including Fabry-Pérot cavities, 6,15,18,22 ring resonators, 11,13,14,16,19,21 distributed feedback cavities 8,23 and photonic crystals. 10 Many types of materials, such as organic dyes, 6,8,10,11,13,19,20 biomaterials (fluorescent proteins, 16,18,21 vitamins, 15 luciferins 14 ) and products of enzyme-substrate reaction, 22 can be used as the gain medium. To date, nearly all optofluidic lasers are demonstrated with the gain medium dispersed in bulk solution.…”