  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$\,\mathrm{K}$
