Western Illinois University, Physics, Macomb, IL 61455
The electro-optic effect refers to the phenomenon that when an external electric field is applied on a crystal, the optical properties of the crystal, especially its refractive index will be changed. This effect has a short response time of less than one nanosecond. This has brought many important applications in modern science and technology into being, such as laser pulse generation, high-speed photography, laser communication and optical data processing. In this talk we will present our experiment of modulating the intensity of a laser beam using the transverse electro-optic modulation in a lithium niobate crystal. We measured the half-wave voltage of the crystal used in the experiment, at which the electro-optic effect induces a phase shift of half a wave between the two polarization eigenmodes of the light inside the crystal, and the polarization plane of the light is rotated by a right angle. Linear modulation of light intensity is achieved when the crystal is working at one half of the value of its half-wave voltage, where the output light intensity faithfully follows the electronic modulation signal. Frequency-doubling distortion occurs at certain applied voltages where the output light is minimized or maximized. Our device can also be used to study the electro-optic coefficients and the interference patterns of light in anisotropic crystals.
[Abstract (DOCX)]