A frequency doubling electro-optic modulation system for Pockels effect measurements: Application in LiNbO3

Abstract

A novel system is presented which is capable of measuring with high accuracy the linear (Pockels) electro-optic effect by means of a new dynamic (ac) method. This method is based on the observation of the photodetected output obtained from a Senarmont-type ellipsometric system with an ac (modulating) voltage being applied onto the electro-optic sample under test. This observation is made on a high sensitivity oscilloscope and allows us to determine accurately the null point of the system by locating the position of the analyzer that produces in the output a characteristic and abrupt doubling of the (modulation) frequency. By locating this frequency doubling position without and with electric field one can finally determine the corresponding electro-optic coefficients. Theoretical analysis and considerations of practical interest are presented in the article and show that the system in question can ensure reduced errors and increased sensitivity. Also, experimental evidence in support of the expected performance is obtained by implementing and applying the system for the measurement of the composite electro-optic coefficient rc of LiNbO3 for various temperatures in the range of 17–20 °C.

Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance

“…Stark effect). The widely used lithium niobate (LiNbO 3 ) modulators based on Pockels effect and III-V semiconductor-based quantumconfined Stark effect modulators are two examples of voltage-driven EOMs [4][5][6]. Incidentally, the performance characteristics of both current-driven and voltage-driven modulators are essentially similar, except that the latter is bounded by limits set to avoid electrical breakdown in the active device region.…”

Composition dependence of the electro‐optic properties of iron‐doped lithium niobate crystals mounted as bulk modulator

“…The minimum‐transmission point, often called the frequency doubling point can be very precisely located when a very sharp narrow‐band filter is used with a high‐sensitivity oscilloscope for the observation of the frequency doubling of the output signal at the extinction shown very clearly on the oscilloscopic screen. This fact makes advantageous the location of the electro‐optical arrangement at this operating point for the use of the so‐called “frequency doubling electro‐optic modulation” or FDEOM method or one of other frequency doubling techniques to determine accurately the static phase retardation variation due to the natural birefringence changes or to the various kinds of EO retardations including the static or dc phase retardation Γ dc caused by the applied dc voltage V dc onto the sample. The FDEOM method will be used for the determination of the static EO coefficients of our samples under tests.…”

Unprecedented Electro‐Optic Performance in Lead‐Free Transparent Ceramics

“…Figure a compares the EO performance of BXT with other EO materials. The value of r c for BXT is more than twenty times higher than the state‐of‐the‐art material LN (commonly r c = 20 pm V −1 ) . This is also a substantial improvement over the standard high‐performance EO materials BaTiO 3 ( r c = 96 pm V −1 and PLZT (Pb 0.88 La 0.12 (Zr 0.4 Ti 0.6 ) 0.97 O 3 , r c = 136 pm V −1 ) .…”

“…For decades lithium niobate (LN), a material belonging to the displacive ferroelectric family, has been ubiquitous in the EO industry finding use in a vast array of devices including amplitude modulators (Pockels cells), phase modulators, beam deflectors, etc . The primary drawback of LN is that it has a relatively low r c (= 20 pm V −1 ), which, as Equation states, requires that high voltages and/or thick materials be used in LN‐based devices. This leads to substantial capital costs in terms of both material (large or multiple crystals requirements) and auxiliary (high‐voltage power supplies) expenses.…”