Linear Electro-Optic Effects in KH_2PO_4 and Its Isomorphs

Abstract

The linear electro-optic coefficients of KH₂PO₄ and a number of its isomorphs have been measured at room temperature using dc voltages. The results at 546 nm are as follows: r₆₃ = 10.3±0.1×10⁻¹² m/V for KH₂PO₄, 10.9±0.1×10⁻¹² m/V for KH₂AsO₄, and 13.0±0.2×10⁻¹² m/V for RbH₂AsO₄; r₄₁ = 8.77±0.14×10⁻¹² m/V for KH₂PO₄, 24.5±0.4×10⁻¹²m/V for NH₄H₂PO₄, 12.5±0.4×10⁻¹² m/V for KH₂AsO₄, and 8.8±0.4×10⁻¹² m/V for KD₂PO₄ which was about 90% deuterated. A transverse modulator based on a single 45° Y-cut crystal of NH₄H₂PO₄ is proposed which requires only 45 V rms for 50% amplitude modulation of 632.8 nm light.