Pockels Coefficients Characterization of Pure and Iron Doped Lithium Niobate Using Adaptive Optics and the Czochralski Crystal Growth Technique

摘要

We have measured the r_c (effective electrooptical coefficient) of pure and doped Ferroelectric Lithium Niobate (LN) using a single beam, null detection polarimeter. The polarimeter is adjustable between two adaptive optics configurations - an iris hard stop beam pattern on the one hand and a diffractive optics generated top-hat beam on the other. Through the measurements, we clearly show the need to control thermal heating of LN due to transmitted laser beam. The required heating control has been implemented using a fabricated metallic heat sink called a "Cold Finger." In addition to its electrooptical properties, LN possesses a combination of unique piezoelectric, pyroelectric, and photorefractive properties. These properties make it suitable for applications in optical devices as frequency doublers, modulators, switches, and filters in communication systems and holographic recording medium. We present the classical microscopic anharmonic oscillator description for generating Pockels coefficients, and briefly describe the polarimetry measurement system. Finally, the growth of pure and iron doped lithium Niobate is also described using an Automatic Diameter Control Czochralski Design growth technique. Here, the results of growth, electrooptic measurements, adaptive optics implementation and some physical properties are compared and presented.