Study of Pyroelectric Suppression Method for LiNbO₃ E-O Modulator

Abstract

The pyroelectric effect in ${\mathbf {LiNbO}}_{\mathbf {3}}$ electro-optic (E-O) modulators leads to bias instability in temperature variation environments. In this study, the pyroelectric model of X-cut ${\mathbf {LiNbO}}_{\mathbf {3}}$ modulator is established for the first time. Simulations of pyroelectric responses under a fixed rate of 2 K/min are conducted, testing two suppression methods: grounding the $\boldsymbol {\pm Z}$ polarization planes and adding surface grounded electrodes, with the latter showing a decrease in the pyroelectric voltage drop by 29.75%. The temperature experiment on the fabricated X-cut ${\mathbf {LiNbO}}_{\mathbf {3}}$ modulator with foldback form reveals that short-circuiting the electrodes could eliminate the pyroelectric pulse discharge phenomenon. Further coating electrically conductive adhesive(ECA) to act as grounded electrodes could suppress pyroelectric secondary oscillations, which shows a reduction of 44.96%. The proposed pyroelectric suppression methods provide a potential improvement strategy for enhancing bias stability in phase-sensitive devices based on ${\mathbf {LiNbO}}_{\mathbf {3}}$ materials.