In　this　paper,　we　present　what　we　believe　is　the　first　demonstration　of　a　new　rectangular　KD*P　crystal　as　an　electro-optic　switch　and　calculations　of　the　stress-induced　birefringence　and　depolarization　loss　in　the　crystal.　We　simulated　and　experimentally　demonstrate　the　thermal　depolarization　loss　of　crystal　in　both　cylindrical　and　rectangular　shape.　The　results　show　that　by　using　a　rectangular　KD*P　crystal,　the　effects　of　the　thermally　induced　birefringence　and　depolarization　can　be　lessened.　(C)　2017　Optical　Society　of　America