Dye-doped cholesteric-liquid-crystal room-temperature single-photon source

Abstract

Fluorescence antibunching from single terrylene molecules embedded in a cholesteric-liquid-crystal host is used to demonstrate operation of a room-temperature single-photon source. One-dimensional (1-D) photonicband-gap microcavities in planar-aligned cholesteric liquid crystals with band gaps from visible to near-infrared spectral regions are fabricated. Liquid-crystal hosts (including liquid crystal oligomers and polymers) increase the source efficiency, firstly, by aligning the dye molecules along the direction preferable for maximum excitation efficiency (deterministic molecular alignment provides deterministically polarized output photons), secondly, by tuning the 1-D photonic-band-gap microcavity to the dye fluorescence band and thirdly, by protecting the dye molecules from quenchers, such as oxygen. In our present experiments, using oxygen-depleted liquid-crystal hosts, dye bleaching is avoided for periods exceeding one hour of continuous 532 nm excitation. IntroductionA single-photon source (SPS) [1, 2] that efficiently produces photons with antibunching characteristics [3] is a pivotal hardware element for quantum communication technology [4][5][6]. Using a SPS, secure quantum communication will prevent any potential eavesdropper from intercepting a message with a secure key without the receiver noticing [4]. Quantum communication has a potential large market [7,8], but its practical realization is held back in part because of the difficulties in developing robust sources of antibunched photons on demand. In another implementation, a SPS becomes the key hardware element for quantum computers with linear optical elements and photodetectors [9][10][11][12].In spite of several solutions for SPSs presented in the literature, significant drawbacks remain. They are the reason why current quantum communication systems are baud-rate bottlenecked, causing photon numbers from ordinary photon sources to attenuate to the single-photon level (approximately 0.1 photon per pulse

Lasing Characteristics of Dye-Doped Cholesteric Liquid Crystal

“…Svetlana G. Lukishova et al used fluorescence antibunching from single terrylene molecules embedded in a cholesteric liquid crystal host to demonstrate operation of a room temperature single photon source [34]. One-dimensional photonic band gap micro cavities in planar aligned cholesteric liquid crystals with band gaps from visible to near-infrared spectral regions were fabricated.…”

Room temperature source of single photons of definite polarization

“…In addition to emitter alignment and self-assembled structures with photonic band-gap properties, such a host with special treatment (oxygen depletion) can protect the emitters from bleaching. In [35][36][37], we reported on a significant diminishing of dye bleaching by saturation of liquid crystals with helium. In that work molecules did not bleach for periods of more than one hour under continuous wave (cw) excitation [35][36][37].…”

“…In [35][36][37], we reported on a significant diminishing of dye bleaching by saturation of liquid crystals with helium. In that work molecules did not bleach for periods of more than one hour under continuous wave (cw) excitation [35][36][37]. (The first impressive experiments on avoiding dye bleaching in oxygen-depleted hosts were reported in [9] and [30].…”

“…Recently we reported the first demonstration of dye-fluorescence antibunching in liquid crystal hosts [35][36][37] that is evidence of the single-photon nature of the source. We prepared 1-D photonic crystals (figure 1) and 2-D hexagonal structures (figure 2) in cholesteric liquid crystals as well [35][36][37]46].…”

“…To date, three approaches have been suggested for room-temperature SPSs: single molecules [8][9][10][29][30][31][32][33][34][35][36][37], colloidal semiconductor quantum dots (nanocrystals) [38,39], and colour centres in diamond [11,[40][41][42][43]. The colour-centre source suffers from the challenge that it is not easy to couple out the photons and that the spectral bandwidth of the light is typically quite large ($120 nm).…”