Enhanced Extinction Ratio in QKD Transmitters Using On-Chip Saturable Absorbers

IEEE Photonics Technology Letters 2026 Open access

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Authors: Julian Konig, Ozan Çirkinoglu, Rajib Ratan Ghosh, Martijn J. R. Heck, Xaveer J. M. Leijtens
DOI: 10.1109/lpt.2026.3661870
Cited by: 0

Abstract

We demonstrate an integrated quantum key distribution (QKD) transmitter with enhanced extinction ratio (ER) using a monolithically integrated saturable absorber (SA). Since the light is later attenuated to the weak-coherent-state level, the additional signal loss in the SA does not impair performance. The SA improves the ER by 3.6 dB at 1 GHz, corresponding to an estimated ∼50% relative reduction in quantum bit error rate and a ∼17% increase in secret key rate, offering a compact, low-complexity route to improved secure key rates in practical QKD systems.

Fields of Study & Subjects

Quantum Information and Cryptography Quantum optics and atomic interactions Semiconductor Quantum Structures and Devices

Publication details

Journal / source
IEEE Photonics Technology Letters
Volume
38
Issue
10
Pages
659–662
Publication date
6 February 2026
Language
EN