Fiber-Based Bidirectional Solid-State Single-Photon Emitter Based on Semiconductor Quantum Dot

Abstract

Fiber-based bidirectional photon detection from nanoscale emitters and photon antibunching behavior between two outputs of two single-mode fibers (SMFs) are experimentally demonstrated. Flakes containing the epitaxially grown quantum dots (QDs) are mechanically fixed by both sides with the edge faces of the SMF patch cables. The emitting photons from a single QD are directly taken out of both sides through the SMFs. Single-photon emission between two SMF outputs is confirmed by detecting nonclassical antibunching in second-order photon correlation measurements. This simple optomechanical alignment-free single-photon emitter is advantageous because of its robust stability of more than three months and low-cost fabrication.Semiconductor quantum dots (QDs) are attractive nanoscale structures for solid-state nonclassical light sources and are expected to play key roles in a quantum information network. 1-3) Above all, single QDs fabricated by epitaxial growth can serve as stable and bright photon emitters. Recently, significant progress of far-field optical coupling to a single semiconductor QD has been achieved by the Purcell effects with elaborated microcavity structures. [4][5][6][7][8][9] However, direct coupling of emitted photons to single-mode fiber (SMF) without exposure to the free-space, air or vacuum, is preferable for future applications. Indeed, various efforts have been made to directly couple a nanoscale photon emitter with a conventional SMF from the perspective of consistency with an existing optical fiber infrastructure. Several groups reported the efficient extraction of photons from a nanoscale emitter directly into an optical fiber by using a tapered fiber, 10) nanophotonic directional coupler, 11) integration of telluride fiber, 12) and direct placing on the fiber facet by an atomic force microscope. 13) In these approaches, no optical loss occurred at coupling from the free-space into optical fibers. From a scientific as well as engineering viewpoint, the long-term stability is another of the most important conditions for a nanoscale photon emitter.This study reports a simple fabrication of a bidirectional solid-state single-photon emitter based on epitaxially grown InAs QDs, which has a long-term stability and also a high po- * E-mail address: hirotaka@cris.hokudai.ac.jp 1/8Submitted to Applied Physics Express We used a fiber-pigtailed laser diode (Thorlabs, LPS-830-FC) that emits at 830 nm as an excitation source with the laser beam arriving at the flakes from the right side of the SMF.To clean up laser spectral noise, a long-pass filter and two short-pass filters were inserted into the laser beam (Thorlabs, FEL0800 and FES0850, respectively). The QD emissions were extracted using two SMFs, corresponding to the reflection (right side) and transmission (left side) configurations in the free-space optical measurement system. To spatially separate the emissions in the reflection direction, a fiber-based dichroic beamsplitter module (Optoquest, custom-made product) was used. The emission was dis...

Fiber-coupled pillar array as a highly pure and stable single-photon source

“…On the other hand, direct contact of SPSs to a fiber end surface 11,[22][23][24][25][26][27] has also been examined because of the guarantee of a simple, stable optical coupling. In our previous work, 24,25 a semiconductor flake containing InAs QDs was sandwiched by two single-mode fibers (SMFs).…”

“…On the other hand, direct contact of SPSs to a fiber end surface 11,[22][23][24][25][26][27] has also been examined because of the guarantee of a simple, stable optical coupling. In our previous work, 24,25 a semiconductor flake containing InAs QDs was sandwiched by two single-mode fibers (SMFs). It had a mechanically solid structure, and once it was set in the liquid-He vessel, it worked as a stable photon source until the liquid He was exhausted.…”

Bright single-photon source based on an InAs quantum dot in a silver-embedded nanocone structure

“…Direct contact of this kind of photon sources to a single-mode fiber will provide a fiberbased photon source with long-term stability. 16 With this metal-embedded pillar structure, we have observed the photon-extraction efficiency of $8% (efficiency collected by the first lens with the numerical aperture (NA) of 0.42).…”

“…Direct contact of this kind of photon sources to a single-mode fiber will provide a fiberbased photon source with long-term stability. 16 With this metal-embedded pillar structure, we have observed the photon-extraction efficiency of $8% (efficiency collected by the first lens with the numerical aperture (NA) of 0.42).14 In this case, GaAs substrates were removed by mechanical cleavage during the metal-embedding process, and hard metals were necessary for the sample preparation. Therefore, titanium (Ti) and/or niobium (Nb) hard metals were selected for the embedding metals in these samples.…”

Metal-coated semiconductor nanostructures and simulation of photon extraction and coupling to optical fibers for a solid-state single-photon source

“…Since many QDs are present outside the nanocavity area, their photon emission couples to the core of the SMF and this tends to mask the single photon emission from a single QD in the nanocavity. As a preliminary trial, we demonstrated a QD emitter coupled to SMF facets in bidirectional configuration [49].…”