Experimental platform for the visual display of the Pockels effect in electro-optic crystals: Design and pedagogical application

The Pockels effect is a foundational principle in the interdisciplinary field of optics and electromagnetism. However, existing experimental methods are incapable of directly measuring the electro-optic phase delay. These methods present several limitations, including dependence on optical power, a high threshold for experimental comprehension, and a disconnect between theoretical principles and concrete cognition. This paper proposes a visualized measurement platform for the Pockels effect that intuitively presents the dynamic variation of electro-optic phase delay under voltage modulation. The platform exhibits core performance characteristics of a wide measurement range and high linearity. The integration of simulation modeling with physical experiments in the teaching process is shown to facilitate the establishment of a concrete correlation between the electric field and phase delay for students. This approach also enhances comprehension of the Pockels effect and improves the quality and efficiency of experimental instruction.

The visualization platform for measuring the Pockels effect is based on a linear demodulation mode of electro-optic phase delay, implemented through both simulation and experimentation. The specific technical route is as follows. A laser generates linearly polarized light using a polarizer, which then passes through a BGO crystal and a quarter-wave plate. The application of an electric field modulation induces rotation of the polarization plane of the linearly polarized light. The emerging light subsequently passes through an S-wave plate and a polarizer, where the S-wave plate converts linear polarization into radial polarization. When combined with a polarizing filter, the linearly polarized light is transformed into a light and dark gradient ring. The ring rotates in response to changes in the polarization plane angle. Accordingly, real-time detection of the electro-optic phase delay is achieved by observing the rotation of the ring. An image-processing system is proposed to determine the rotation angle of the ring, incorporating image preprocessing, edge detection, and circular positioning. The rotation angle and the corresponding electro-optic phase delay are obtained by plotting the radial gray-value distribution of the ring and calculating the horizontal displacement of the gray-value characteristic curve.

Simulation results show that the proposed measurement system produces a ring spot that rotates with changes in the applied voltage. The electro-optic phase delay angle is found to be twice the rotation angle of the ring. Physical experimental results demonstrate that the system can achieve a dynamic measurement range of 0 to 360° of electro-optic phase delay. The observed phase delay varies linearly with the applied modulation voltage. The measured linearity is 0.47%, with a maximum error not exceeding 1.5%.

This paper provides a comprehensive evaluation of the feasibility of a visual display platform for demonstrating the Pockels effect in electro-optic crystals from three perspectives: theoretical derivation, simulation modeling, and experimental verification. The use of simulation models enhances students' understanding of the underlying principles of the Pockels effect, while the incorporation of physical experiments strengthens their practical skills. Overall, the platform transforms the abstract principle of the Pockels effect into an intuitive rotation of a light pattern, thereby establishing a direct visual connection between the electric field and phase delay and enabling students to apply theoretical knowledge more effectively.