Frequency dispersion of electro-optical properties over a wide range by means of time-response analysis

Abstract

We show that a Z-transform-based time-response analysis of the electro-optical response of a crystal to a step voltage with a short rise time allows one to obtain the dispersion of the electro-optical coefficients over a wide frequency range. We describe the method employed and present the results obtained for the main electroptic coefficients (r22, r61, and rc) of a standard LiNbO3 crystal. We also show that this method is able to provide even small values of the electro-optic coefficient as well as the dispersion within a wide frequency range, which is limited only by the rise time of the step voltage.

Electro-optic properties of singly and doubly doped lithium niobate crystal by rare earth elements for optoelectronic and laser applications

“…We have investigated, at room temperature and using a He-Ne laser (633 nm), the unclamped EO coefficients r 13 and r 13 using a Mach-Zehnder type interferometric technique with light propagation along the x-axis, polarization parallel to the y and z axes, respectively, for the two coefficients, and an applied electric field parallel to the z-axis of the crystals. The associated method is the "Modulation Depth Method" (MDM) previously described in references [71,72]. As a reminder, MDM is a dynamic method in which the EO coefficient is calculated from the measurement of the modulated beam amplitude induced by an ac-voltage applied on the sample under test.…”

“…to the so-called linear working point corresponding to the (I max -I min )/2 point, with I max and I min the maximum and minimum of the transmitted intensity. The absolute value of the effective EO figure of merit can be determined from the experimental intensities and voltage measurements within an equation having the form [72,73]…”

Investigation of contrast ratio dependence on the angular deviation of the laser beam direction from the optical axis of Pockels cells based on the beta barium borate crystal

“…The contrast ratio is one of the main parameters of the Pockels cell [12]. It is expressed as the ratio of the s and p polarisation beams intensity on the output of the Pockels cell crystal [13]. The contrast ratio decreases when the depolarisation of the light inside the Pockels cell crystal increases.…”

The electro-opticr22coefficients and acoustic contributions in LiTaO3crystal

“…The present paper exhibits the results of EO determinations in LT rega rding the EO coefficients r T 22 and r S 22 ,w ith emphasis placed on the acoustic contribution to the EO effect and the true value of the r 22 coefficient for a long crystal sample. The above measurements have been performed using, for increased versatility and accuracy, elaborate techniques such as the frequency-doubling EO-modulation (FDEOM) method and the step-voltage time-response (TRM) method [11,12]. The first method is more appropriate for dc or low EO-modulation frequencies, while the latter yields values of EO coefficient over a wide frequency range and allows us to obtain and analyse the corresponding frequency dispersion of the EO effect.…”