Polarization investigation of a tunable high-speed short-wavelength bulk-micromachined MEMS-VCSEL

Davani, H. A.; Kögel, Benjamin; Debernardi, Pierluigi; Grasse, Christian; Gierl, Christian; Zogal, Karolina; Haglund, Åsa; Gustavsson, Johan S.; Westbergh, Petter; Gründl, T.; Komissinskiy, Philipp; Bitsch, Thorsten; Alff, Lambert; Küppers, Franko; Larsson, Anders; Amann, Markus‐Christian; Meißner, P.

doi:10.1117/12.908262

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…and a comparison of the chips is presented in Figure 2c. Evidently, the spectral separation of the fundamental modes of the chips ((∆λ) max ≈ 0.8 nm) has to be compensated in a future version either by thermal tuning of individual diodes or by using MEMS tunable VCSELs [25].…”

Section: Generation Of Faint Unpolarized Laser Pulsesmentioning

confidence: 99%

Design and Evaluation of a Handheld Quantum Key Distribution Sender module

Vest

Rau

Fuchs

et al. 2015

IEEE J. Select. Topics Quantum Electron.

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Currently most quantum key distribution (QKD) experiments are focusing on efficient long-distance implementations. Yet the recent development of miniaturized photonic modules and integrated quantum optics circuits could open new perspectives toward secure short-distance communication for daily-life applications. Here, we present the design of a new integrated optics architecture with an effective size of 25 mm\, \times \,2 mm\, \times \, 1\,mm. Our objective is to obtain an ultraflat microoptics QKD add-on suitable for integration into handheld platforms such as smartphones. In this context, we evaluated the suitability of various optical subsystems. We tested an array of four vertical cavity surface emitting lasers (VCSEL) with highly similar emission properties capable of producing subnanosecond near-infrared pulses at 100-MHz repetition rate. As short pulses exhibit a low polarization degree, their polarization can be externally controlled by a micropolarizer array. The fabrication of such elements is quite straightforward using standard lithographic techniques and extinction ratios up to 29 \,dB have been measured. To guarantee spatial indistinguishability of the qubits, we investigate the option of using low-birefringence, single-mode waveguide array manufactured via femtosecond laser micromachining

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Section: Generation Of Faint Unpolarized Laser Pulsesmentioning

confidence: 99%

Design and Evaluation of a Handheld Quantum Key Distribution Sender module

Vest

Rau

Fuchs

et al. 2015

IEEE J. Select. Topics Quantum Electron.

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“…We observed a spectral distinguishability of the 4 off-theshelf VCSELs due to fabrication imperfections, however, for our proof-of-principle demonstration we accept this open side channel. When commercializing such systems in the future, this could be avoided, e.g., by proper selection of the diodes prior to the assembly of the module [39], by the use of MEMStunable structures [41,42] or by spectral filtering once the spectra of the four diodes start overlapping.…”

Section: B Characterization Of the Sender Unitmentioning

confidence: 99%

Quantum Key Distribution with a Hand-held Sender Unit

Vest¹,

Freiwang²,

Luhn³

et al. 2022

Preprint

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Quantum key distribution (QKD) is a crucial component for truly secure communication, which enables to analyze leakage of information due to eavesdropper attacks. While impressive progress was made in the field of long-distance implementations, user-oriented applications involving shortdistance links have mostly remained overlooked. Recent technological advances in integrated photonics now enable developments towards QKD also for existing hand-held communication platforms.In this work we report on the design and evaluation of a hand-held free-space QKD system including a micro-optics based sender unit. This system implements the BB84-protocol employing polarization-encoded faint laser pulses at a rate of 100 MHz. Unidirectional beam tracking and live reference-frame alignment systems at the receiver side enable a stable operation over tens of seconds when aiming the portable transmitter to the receiver input by hand from a distance of about half a meter. The user-friendliness of our system was confirmed by successful key exchanges performed by different untrained users with an average link efficiency of about 20 % relative to the case of the transmitter being stationarily mounted and aligned. In these tests we achieve an average quantum bit error ratio (QBER) of 2.4 % and asymptotic secret key rates ranging from 4.0 kbps to 15.3 kbps. Given its compactness, the versatile sender optics is also well suited for integration into other free-space communication systems enabling QKD over any distance.

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