Cryogenic electro-optic modulation in titanium in-diffused lithium niobate waveguides. (1st July 2022)

• Record Type: Journal Article
• Authors: Thiele, Frederik; vom Bruch, Felix; Brockmeier, Julian; Protte, Maximilian; Hummel, Thomas; Ricken, Raimund; Quiring, Viktor; Lengeling, Sebastian; Herrmann, Harald; Eigner, Christof; Silberhorn, Christine; Bartley, Tim J
• Is Part Of: JPhys photonics. Volume 4:Number 3(2022)
• Publication Date: 2022-07-01
• Subjects: lithium niobate -- photonics -- cryogenic -- low temperature -- modulator -- electro-optics; Photonics -- Periodicals; 621.365
• DOI: 10.1088/2515-7647/ac6c63
• Languages: English
• ISSNs: 2515-7647

Abstract

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 π / 2 of these modulators increases, due to the decrease in the electro-optic effect, by 74% for the phase modulator, 84% for the directional coupler and 35% for the polarisation converter below 8.5 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 n m while cooling the device down to 5 K . The polarisation converter uses periodic poling to phasematch the two orthogonal polarisations. The phasematched wavelength of the utilised poling changes by 112 n m when cooling to 5 K .