Abstract
A novel method for determining the electro-optic (EO) coefficient γ 22 of lithium niobate and its dispersion using photoelastic modulation is presented. A spectroscopic polarimetry was constructed with the photoelastic modulator (PEM), and a monochromator was selected to automatically scan the wavelength of a light source. Phase retardation induced by an EO sample was loaded into the modulation signals to demodulate the EO coefficients. The PEM and data processing were controlled in the same field programmable gate array (FPGA), and the DC and harmonic terms were extracted simultaneously by employing digital phase-locked technology. An experimental system was built to analyze the principle of this scheme in detail. After the modulation phase retardation amplitude of the PEM was precisely calibrated, the EO coefficient γ 22 of a Y-cut lithium niobate crystal plate was measured in the spectral range from 0.42 to 0.8 µm. The experimental results demonstrated that the measurement sensitivity of the system was 1.1 × 10 − 14 m / V for a sampling time of 198.9 ms. Plotting the measured results against the light wavelength, the dispersion of the EO coefficients was obtained similar to the Cauchy dispersion formula γ 22 = 5.31 × 10 − 12 + 4.071 × 10 − 13 λ 2 + 7.184 × 10 − 14 λ 4 in the visible light range. This method is suitable for studying dispersion of the EO coefficients of crystals as well as of thin films and two-dimensional materials.
Highlights
As the demands for high-speed and large bandwidth information processing are increasing, electro-optic (EO) devices such as modulators, sensors, deflectors, multipliers, switches, and spatial light modulators, which are developed using EO effect, are gaining important applications in data processing and signal transmission [1,2,3,4,5,6]
EO coefficients are quantitative parameters of the EO effect, their accurate measurements are the key for designing these EO devices, and a study on the dispersion of the EO coefficients is of great significance for designing the EO devices that are suitable for wide spectrum applications [7,8,9,10]
This paper focuses on the study of the dispersion of the EO coefficients in a wide wavelength range based on the photoelastic modulation
Summary
As the demands for high-speed and large bandwidth information processing are increasing, electro-optic (EO) devices such as modulators, sensors, deflectors, multipliers, switches, and spatial light modulators, which are developed using EO effect, are gaining important applications in data processing and signal transmission [1,2,3,4,5,6]. There are many measurement methods of the EO coefficients to be explored, such as Mach–Zehnder, Michelson, and Fabry-Perot interference methods for phase measurement, as well as half-wave voltage and Senarmont polarimetric methods for phase retardation measurement. Half-wave voltage and Senarmont polarimetric methods determine the EO coefficients by measuring the phase retardation between two orthogonally polarized components that pass through the sample, and the intensity of light at the extreme value must be determined [16,17]. The photoelastic modulation has a large modulation frequency, high modulation efficiency, and satisfactory modulation stability Considering these excellent polarization modulation properties, we have realized a high-speed, accurate, and sensitive measurement for the EO coefficients by using a PEM in our previous work [24]. A novel measurement method for the dispersion of the EO coefficients is developed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
