Nanooptics and photonics

Single-photon source at telecom wavelengths based on InGaAs/GaAs quantum dots: towards practical application
Kravets O.1, Musiał A.1, Srocka N.2, Żołnacz K.3, Mikulicz M.1, Holewa P.1, Jasiński J.1, Große J.2, Urbańczyk W.3, Schneider P.-I.4, Burger S.4,5, Poturaj K.6, Wójcik G.6, Mergo P.6, Dybka K.7, Dyrkacz M.7, Dłubek M.7, Quandt D.2, Strittmatter A.2, Rodt S.2, Reitzenstein S.2 and Sęk G.1
1 OSN Laboratory, Wrocław University of Science and Technology, Poland.
E-mail: oleh.kravets@pwr.edu.pl
2 Institute of Solid State Physics, Technical University of Berlin, Germany
3 Fiber Optics Group, Wrocław University of Science and Technology, Poland
4 JCMwave GmbH, Berlin, Germany
5 Zuse Institute Berlin, Germany
6 Laboratory of Optical Fiber Technology, UMCS, Lublin, Poland
7 Fibrain Sp Zoo, Zaczernie, Poland

The practical realization of quantum communication requires single-photon sources (SPSs) compatible with existing silica fiber networks operating in the telecom bands. QD-based SPSs operate in cryogenic temperatures whereas elevated temperatures are preferable for practical applications [1]. This work aims in development of practical all-in-fiber SPS in the telecom spectral range (1.3 µm).
Self-assembled strain-engineered InGaAs/GaAs QDs are deterministically incorporated into mesa-structures with numerically-optimized design [2] grown by MOCVD. Free-space autocorrelation measurements at 30 K revealed high-purity single-photon emission with g(2)(0)=0.01 proving high relevance of investigated QD material [3]. For sample directly glued to a fiber ferrule and cooled down in cryogenic-free Stirling cryocooler g(2)(0)=0.37 was reached at 40K. 

1.	Dusanowski Ł. et al. Triggered high-purity telecom-wavelength single-photon generation from p-shell-driven InGaAs/GaAs quantum dot // Opt. Express -2017.-25.-P. 304931- 304939.
2.	Schneider P.-I. et al. Numerical optimization of the extraction efficiency of a quantum-dot based single-photon emitter into a single-mode fiber // Opt. Express -2018.-26.-P. 8479-8492.
3.	Srocka N. et al. Enhanced photon-extraction efficiency from InGaAs/GaAs quantum dots in deterministic photonic structures at 1.3 µm fabricated by in-situ electron-beam lithography // AIP Adv. -2018.-8.-P. 085205(1-9).