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The drift issue induces slow drifting of the optimum operating point for high efficiency or large nonlinearities in analog optical links, and requires complex control of the offset bias voltage for achieving high extinction ratio in digital optical links. We discuss and analyze the different sources of the drift in commercially LiNbO 3 Mach-Zehnder modulators. The different extrinsic and intrinsic origins are compared in terms of phase shift and the different corresponding orders of magnitude are given, pointing out the predominant role of the intrinsic (dc) drift. We show the large role played by the electrical inhomogeneities at the surface of the LiNbO 3 substrate by highlighting the link between the time dependence of the dc drift and the electrical conductivity measured at the surface and in the volume of the LiNbO 3 substrate. This allows to propose a solution to the drift issue which consists in the engineering of the electrical conductivity of the lithium niobate substrate.

The majority of patients presented taste and olfactory changes soon after surgery independently of type of procedure. Patients submitted to LGBP referred more often a different smell in food. Higher %EWL was observed in patients presenting any food aversion, especially in the LGBP group.

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The intensity, the peak wavelength and the decay time of polaron photoluminescence in congruent lithium niobate are measured versus temperature from 77 K to 290 K. The radiative relaxation shows quasi athermal behaviour (τ R ≈ 9 µs) whereas the nonradiative relaxation follows arrhenius law with activation energy of 220 meV. The crossing point between radiative and nonradiative lifetimes is about 210 K.1 Introduction Lithium niobate (LiNbO 3 , LN) is of great interest for optical applications owing to its large electro-optic and non linear optical coefficients. Several physical properties involved in device operation are sensitive to the concentration of point defects and to the chemical reduction degree of the material. In particular the defect structure of LiNbO 3 is attributed to the presence of Nb in the lithium site (so called niobium antisite). Niobium antisite defects Nb Li 5+ are able to trap an electron on an energy level below the conduction band, giving a small bound polaron Nb Li 4+ [1]. This defect plays a major role in light-induced phenomena (photoconductivity, light-induced absorption, photorefractive effect [2][3][4]. Previous studies show that excitation of congruent lithium niobate in the visible range always gives a photoluminescence (PL) band in the near infrared, which is attributed to polaron defects [5]. Recently the PL efficiency of congruent LN has been measured versus temperature under continuous wave excitation at 355 nm [6]. The main aim of the present work is to study the PL decay after short pulse excitation and to measure the relaxation time versus temperature.