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arXiv · 2202.00306

Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides

Frederik Thiele·Felix vom Bruch·Julian Brockmeier·Maximilian Protte·Thomas Hummel·Raimund Ricken·Victor Quiring·Sebastian Lengeling·Harald Herrmann·Christof Eigner·Christine Silberhorn·Tim J. Bartley
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Abstract

Lithium niobate is a promising platform for integrated quantum optics. In this platform we aim to efficiently manipulate and detect quantum states by combining superconducting single photon detectors and modulators. The cryogenic operation of a superconducting single photon detector dictates the optimisation of the electro-optic modulators under the same operating conditions. To that end, we characterise a phase modulator, directional coupler, and polarisation converter at both ambient and cryogenic temperatures. The operation voltage $V_{\pi/2}$ of these modulators increases due to the decrease of the electro-optic effect by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5$\,\mathrm{K}$. The phase modulator preserves its broadband nature and modulates light in the characterised wavelength range. The unbiased bar state of the directional coupler changed by a wavelength shift of 85$\,\mathrm{nm}$ while cooling the device down to 5$\,\mathrm{K}$. The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the used poling changes by 112$\,\mathrm{nm}$ when cooling to 5$\,\mathrm{K}$

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Frederik Thiele, Felix vom Bruch, Julian Brockmeier, Maximilian Protte, Thomas Hummel, Raimund Ricken, Victor Quiring, Sebastian Lengeling, Harald Herrmann, Christof Eigner, Christine Silberhorn, Tim J. Bartley. 2022-02-01. Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides. https://arxiv.org/abs/2202.00306

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