Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 4: Semiconductor Lasers

HL 4.6: Vortrag

Montag, 5. September 2022, 10:45–11:00, H33

Development of a 850 nm VCSEL array for real world QKD via the BB84 and decoy state protocol — •Moritz Birkhold, Michael Zimmer, Sergej Vollmer, Michael Jetter, and Peter Michler — Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Allmandring 3, 70569 Stuttgart

Quantum key distribution offers fundamental advantages over classical key distribution. If done correctly a perfectly private key (e.g. a one time pad) can be exchanged between two parties and any eavesdroping attack will be detected. This could be an intresting feature for e.g. worldwide financial applications but the technological hurdles to overcome are numerous.

Here we show the advances towards a complete eight VCSEL array with an integrated polarization grating in the light emission window, to create quantum states and transmit the quantum key. The basic structure is grown by metal-organic vapor-phase epitaxy (MOVPE). Then this structure is processed to allow data transmission in the GHz regime. Varoius methodes including a co-planar contact geometry are used to achieve this. A vektor network analyzer is than used to measure the scattering parameter as well as the transmission bandwith. Finally a eye diagramm is recorded to determine the data rate. The polarization grating is defined by an electron beam lithography and etched with an ICP machine to allow light output in four different polarizations. The pulses of the eight different VCSEL are evaluated for indistinguishability.