Deterministic integration and optical characterization of telecom O-band quantum dots embedded into wet-chemically etched Gaussian-shaped microlenses

Abstract

In the present study, we report on the deterministic integration of quantum dots, emitting in the telecom O-band, into wet-chemically fabricated Gaussian-shaped microlenses which exhibit a surface quality comparable to epi-ready wafers. The slow wet-chemical etching rate enables us to gain control of the lens aspect-ratio and the vertical position with respect to the quantum dot, allowing us to engineer the far field shape to better match the acceptance profile of single-mode fibers. Maximum light enhancement values of around 10 to 16 could be achieved for collection numerical apertures from 0.6 to 0.2, respectively. The current results constitute an important step forward in transferring state-of-the-art performances achieved in the near-infrared regime to the key wavelengths for long distance fiber communication.

Photonic Jet Writing of Quantum Dots Self‐Aligned to Dielectric Microspheres

“…Their maximum collection enhancement is about , even though, for particular geometries of the microlens and for low NA objectives, slightly larger collection efficiencies can be reached. [ 14 ] For glass () microspheres, on the other hand, the collection enhancement consistently exceeds . For large NA objectives () the enhancement ranges between 6 and 10 in the wavelength range of interest ( nm, see Figure S5h, Supporting Information), that is, it is comparable to what can be achieved with high‐ n SILs and microlenses.…”

“…Among these solutions, [ 6 ] the ones that give the best results require a hardly achievable spatial and spectral coupling between the QDs and an external resonator, for example microcavities, [ 7 ] photonic crystal (PhC) cavities alone [ 8 ] or coupled with waveguides, [ 9 ] and circular Bragg gratings. [ 10 ] Thanks to the development of broadband alternatives such as microspheres, [ 11 ] 3D printed microlenses, [ 12–14 ] nanowires, [ 15 ] nanorings alone [ 16 ] or combined with other broadband solutions, [ 17 ] and photonic trumpets (with 95% out‐coupling record efficiency), [ 18 ] the spectral coupling problem has been partially solved, but these devices still require an accurate positioning of the QDs. Moreover, all these techniques require complex nano‐fabrications and/or nano‐manipulations, strongly limiting the scalability of these solutions, which are also irreversible, expensive, and subject to possible failure in the nanofabrication process.…”

InP-Substrate-Based Quantum Dashes on a DBR as Single-Photon Emitters at the Third Telecommunication Window

“…The current quantum-dot-based solutions are mostly limited by collection efficiency of emission to a first lens (or an optical fiber) of the detection/collection system [5,19], which severely hinders their applicability as efficient telecommunication SPS [11,19]. Many photonic structures with QDs have been demonstrated to improve the extraction of emission from a single QD, e.g., photonic crystal cavities [20,21], circular Bragg resonators [22,23], micropillars [17,24,25], also electrically controlled [13], microlenses [26][27][28][29][30], and mesa structures [31][32][33]. Nevertheless, the major progress and the most important milestones in this field concern QDs beyond the third telecommunication window [11,19].…”

Bright Purcell enhanced single-photon source in the telecom O-band based on a quantum dot in a circular Bragg grating

“…30 This allowed for the demonstration of entangled photon pair emission with high brightness and indistinguishability for GaAs QDs emitting around 780 nm 31 as well as In(Ga)As QDs at 900 nm. 32 However, for the telecom regime, most of the results have been demonstrated in the InAs/InP material system [33][34][35][36][37][38] with approaches in the InGaAs/GaAs material system being limited to etched microlenses and mesas, 39,40 dielectric antennas 41 and micropillars. 42 The feasibility of circular Bragg gratings in the telecom regime was suggested with simulations 43 as a promising approach, however, the realization of such a structure was still outstanding.…”