Monolithically integrated single quantum dots coupled to bowtie nanoantennas

Abstract

Deterministically integrating semiconductor quantum emitters [1] with plasmonic nano-devices [2,3] paves the way towards chip-scale integrable [4], true nanoscale quantum photonics technologies [5]. For this purpose, stable and bright semiconductor emitters [6] are needed, which moreover allow for CMOS-compatibility [7] and optical activity in the telecommunication band [8]. Here, we demonstrate strongly enhanced light-matter coupling of single near-surface (< 10 nm) InAs quantum dots monolithically integrated into electromagnetic hot-spots of sub-wavelength sized metal nanoantennas. The antenna strongly enhances the emission intensity of single quantum dots by up to ∼ 16×, an effect accompanied by an up to 3.4× Purcell-enhanced spontaneous emission rate. Moreover, the emission is strongly polarised along the antenna axis with degrees of linear polarisation up to ∼ 85 %. The results unambiguously demonstrate the efficient coupling of individual quantum dots to state-of-the-art nanoantennas. Our work provides new perspectives for the realisation of quantum plasmonic sensors [9], step-changing photovoltaic devices [10], bright and ultrafast quantum light sources [11] and efficent nano-lasers [12].The field of nanoplasmonics [13] has already demonstrated outstanding potential to tailor and enhance electromagnetic fields on sub-wavelength lengthscales [3]. As such it represents the most promising route to interface state-of-the-art electronics with true nano-photonic devices on the same chip [7]. To this end, the study, optimisation and integration of nano-scale plasmonic components, such as antennas [14] and waveguides [4], on highquality semiconductor substrates [15] is essential in order to prove their applicability in real-world applications. Monolithically integrated, self-assembled quantum dots [1] exhibit outstanding electrical and optical properties, they do not suffer from bleaching or blinking and have near-unity internal quantum efficiencies. These properties stem from the efficient decoupling from environmental perturbations in the solid-state matrix material and distinguish self-assembled quantum dots from alternative quantum emitters, such as nitrogen vacancy centres [16], colloidal nano-crystals [6], single molecules [17] or fluorescent dyes [18]. Lithographically defined plasmonic dimer antennas, such as bowties [14], are most prominent amongst the zoo of metallic nanoparticles since they simultaneously provide strong light confinement in subwavelength sized hot-spots, large-range spectral tunability and facilitate electrical access [19] and full control of the emission polarisation [20]. As a result, the quantum dot coupled nanoantennas offer new perspectives to probe light-matter-couplings and cavity quantum electrodynamics (cQED) effects beyond the point-dipole approximation [21].In this Letter, we coupled individual quantum dots to plasmonic nanoantennas to form a novel cQED-system schematically illustrated in figure 1 (a), which consists of near-surface (d ∼ 10 nm) InAs/AlGaAs quantum dots [22] ...

Resonance fluorescence spectrum of aΛ-type quantum emitter close to a metallic nanoparticle

“…In addition, hybrid complexes consisting of self-assembled QDs have been grown and covered with metal nanocrystals [52]. We would like to draw the attention to recent work where the controlled coupling of single QDs to a plasmonic nanoantenna has been demonstrated [10,11,[53][54][55][56]. Therefore, the hybrid system considered here could be fabricated using available growth and positioning technologies for the elements involved.…”

Plasmon-assisted bandgap engineering in dilute nitrides

“…The reported findings demonstrate that bandgap engineering through plasmonic nanostructures represents a versatile and powerful tool to control the optoelectronic properties of dilute nitrides in a spatially controlled way. In particular, the reported study represent a first, pivotal step toward the realization of deterministically coupled optically active semiconductorplasmonic integrated components, of great interest for the practical implementation of quantum information and communication protocols [63]. Indeed, the demonstrated ability to locally manipulate the bandgap energy of hydrogenated dilute nitrides via plasmonic NAs can lead to the realization of spatially controlled QDs, which can be directly coupled with the plasmonic nanostructures used to fabricate them.…”

Novel Plasmonic Nanocavities for Optical Trapping‐Assisted Biosensing Applications

“…[ 1–4 ] However, due to the intrinsic low optical response of small objects, there has been a clear trade‐off between the size of a material and its response to light. [ 5 ] Recently, plasmonic nanostructures have emerged as leading platforms to enhance the weak optical signals of low dimensional materials including quantum dots (QDs), [ 6 ] small molecules, [ 7,8 ] and 2D monolayers. [ 9 ]…”