Ultraviolet (UV) narrowband photodetectors play a critical role in missile detection, flame monitoring, optical communication, etc. It is a great challenge to realize UV narrowband organic ...photodetectors due to wide photo‐harvesting property of organic materials, especially for photomultiplication type organic photodetectors (PM‐OPDs). In this work, a smart strategy is proposed to achieve UV narrowband response by coupling Fabry−Pérot microcavity with PM‐OPDs. PM‐OPDs are realized by using poly(3‐hexylthiophene‐2,5‐diyl):6,6‐phenyl‐C71‐butyric acid methyl ester (100:1, w/w) as active layers, exhibiting broadband response range covering from UV–vis region. Series of optical microcavities consisting of Ag/LiF/Ag with UV spectral selectivity are prepared, which are employed to couple with the PM‐OPDs for achieving UV narrowband response. The UV spectral selectivity of optical microcavity can be optimized by tuning the thickness of spacer layer and mirror layers, which can further regulate the photogenerated electron distribution near Al electrode to optimize the external quantum efficiency (EQE) spectra of the PM‐OPDs coupled with optical microcavity. The optimized PM‐OPDs coupled with optical microcavity exhibit EQE of 9300% at 350 nm and narrowband response with 33 nm full‐width at half‐maximum under −15 V bias. This work indicates that PM‐OPDs coupled with optical microcavity should be an efficient strategy for achieving UV narrowband response.
Optical microcavities possessing ultraviolet (UV) spectral selectivity are coupled with photomultiplication‐type organic photodetectors (PM‐OPDs) based on poly(3‐hexylthiophene‐2,5‐diyl):6,6‐phenyl‐C71‐butyric acid methyl ester (100:1, w/w) as active layers to achieve UV narrowband response. The optimal PM‐OPDs coupled with optical microcavity exhibit 9300% of external quantum efficiency at 350 nm and narrowband response with 33 nm full‐width at half‐maximum under −15 V applied voltage.
Detection of nanoscale objects is highly desirable in various fields such as early‐stage disease diagnosis, environmental monitoring and homeland security. Optical microcavity sensors are renowned ...for ultrahigh sensitivities due to strongly enhanced light‐matter interaction. This review focuses on single nanoparticle detection using optical whispering gallery microcavities and photonic crystal microcavities, both of which have been developing rapidly over the past few years. The reactive and dissipative sensing methods, characterized by light‐analyte interactions, are explained explicitly. The sensitivity and the detection limit are essentially determined by the cavity properties, and are limited by the various noise sources in the measurements. On the one hand, recent advances include significant sensitivity enhancement using techniques to construct novel microcavity structures with reduced mode volumes, to localize the mode field, or to introduce optical gain. On the other hand, researchers attempt to lower the detection limit by improving the spectral resolution, which can be implemented by suppressing the experimental noises. We also review the methods of achieving a better temporal resolution by employing mode locking techniques or cavity ring up spectroscopy. In conclusion, outlooks on the possible ways to implement microcavity‐based sensing devices and potential applications are provided.
Single nanoparticle detection is of critical importance in various fields from fundamental research to practical applications. Optical microcavities are excellent candidates to be employed in ultra‐sensitive sensing due to significantly enhanced light‐matter interaction. The sensing performance can be improved by obtaining better spectral resolution and temporal resolution, and techniques can be applied to realize practical and portable sensors using microcavities.
Planar microcavities with strong light–matter coupling, monolithically processed fully from solution, consisting of two polymer‐based distributed Bragg reflectors (DBRs) comprising alternating layers ...of a high‐refractive‐index titanium oxide hydrate/poly(vinyl alcohol) hybrid material and a low‐refractive‐index fluorinated polymer are presented. The DBRs enclose a perylene diimide derivative (b‐PDI‐1) film positioned at the antinode of the optical mode. Strong light–matter coupling is achieved in these structures at the target excitation of the b‐PDI‐1. Indeed, the energy‐dispersion relation (energy vs in‐plane wavevector or output angle) in reflectance and the group delay of transmitted light in the microcavities show a clear anti‐crossing—an energy gap between two distinct exciton‐polariton dispersion branches. The agreement between classical electrodynamic simulations of the microcavity response and the experimental data demonstrates that the entire microcavity stack can be controllably produced as designed. Promisingly, the refractive index of the inorganic/organic hybrid layers used in the microcavity DBRs can be precisely manipulated between values of 1.50 to 2.10. Hence, microcavities with a wide spectral range of optical modes might be designed and produced with straightforward coating methodologies, enabling fine‐tuning of the energy and lifetime of the microcavities‘ optical modes to harness strong light–matter coupling in a wide variety of solution processable active materials.
Fully solution‐processed microcavities are demonstrated that allow realizing strong light–matter coupling with an organic semiconductor, all enabled by a versatile molecular hybrid material that permits the fabrication of dielectric mirrors with high‐refractive‐index contrast between constituting layers.
Two-dimensional atomic crystals of graphene, as well as transition-metal dichalcogenides, have emerged as a class of materials that demonstrate strong interaction with light. This interaction can be ...further controlled by embedding such materials into optical microcavities. When the interaction rate is engineered to be faster than dissipation from the light and matter entities, one reaches the 'strong coupling' regime. This results in the formation of half-light, half-matter bosonic quasiparticles called microcavity polaritons. Here, we report evidence of strong light-matter coupling and the formation of microcavity polaritons in a two-dimensional atomic crystal of molybdenum disulphide (MoS2 ) embedded inside a dielectric microcavity at room temperature. A Rabi splitting of 46 ± 3 meV is observed in angle-resolved reflectivity and photoluminescence spectra due to coupling between the two-dimensional excitons and the cavity photons. Realizing strong coupling at room temperature in two-dimensional materials that offer a disorder-free potential landscape provides an attractive route for the development of practical polaritonic devices.
An optimal single-photon source should deterministically deliver one, and only one, photon at a time, with no trade-off between the source’s efficiency and the photon indistinguishability. However, ...all reported solid-state sources of indistinguishable single photons had to rely on polarization filtering, which reduced the efficiency by 50%, fundamentally limiting the scaling of photonic quantum technologies. Here, we overcome this long-standing challenge by coherently driving quantum dots deterministically coupled to polarization-selective Purcell microcavities. We present two examples: narrowband, elliptical micropillars and broadband, elliptical Bragg gratings. A polarization-orthogonal excitation–collection scheme is designed to minimize the polarization filtering loss under resonant excitation. We demonstrate a polarized single-photon efficiency of 0.60 ± 0.02 (0.56 ± 0.02), a single-photon purity of 0.975 ± 0.005 (0.991 ± 0.003) and an indistinguishability of 0.975 ± 0.006 (0.951 ± 0.005) for the micropillar (Bragg grating) device. Our work provides promising solutions for truly optimal single-photon sources combining near-unity indistinguishability and near-unity system efficiency simultaneously.
Coherent perfect absorption at an exceptional point Wang, Changqing; Sweeney, William R; Stone, A Douglas ...
Science (American Association for the Advancement of Science),
2021-Sep-10, 2021-09-10, 20210910, Letnik:
373, Številka:
6560
Journal Article
Recenzirano
Odprti dostop
Recently, exceptional points, a degeneracy of open wave systems, have been observed in photonics, acoustics, and electronics. They have mainly been realized as a degeneracy of resonances; however, a ...degeneracy associated with the absorption of waves can exhibit distinct and interesting physical features. Here, we demonstrate such an absorbing exceptional point by engineering degeneracies in the absorption spectrum of dissipative optical microcavities. We experimentally distinguished the conditions to realize an absorbing exceptional point versus a resonant exceptional point. Furthermore, when the optical loss was tuned to achieve perfect absorption at an absorbing exceptional point, we observed its signature, an anomalously broadened line shape in the absorption spectrum. The distinct scattering properties of the absorbing exceptional point create opportunities for both fundamental study and applications of non-Hermitian degeneracies.
The dynamics of a mobile quantum impurity in a degenerate Fermi system is a fundamental problem in many-body physics. The interest in this field has been renewed due to recent ground-breaking ...experiments with ultracold Fermi gases1, 2, 3, 4, 5. Optical creation of an exciton or a polariton in a two-dimensional electron system embedded in a microcavity constitutes a new frontier for this field due to an interplay between cavity coupling favouring ultralow-mass polariton formation6 and exciton-electron interactions leading to polaron or trion formation7, 8. Here, we present cavity spectroscopy of gate-tunable monolayer MoSe2 (ref. 9) exhibiting strongly bound trion and polaron resonances, as well as non-perturbative coupling to a single microcavity mode10, 11. As the electron density is increased, the oscillator strength determined from the polariton splitting is gradually transferred from the higher-energy repulsive exciton-polaron resonance to the lower-energy attractive exciton-polaron state. Simultaneous observation of polariton formation in both attractive and repulsive branches indicates a new regime of polaron physics where the polariton impurity mass can be much smaller than that of the electrons. Our findings shed new light on optical response of semiconductors in the presence of free carriers by identifying the Fermi polaron nature of excitonic resonances and constitute a first step in investigation of a new class of degenerate Bose-Fermi mixtures12, 13.
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