Gc. Bhar et P. Kumbhakar, Comment on "ZnGeP2 birefringence and its temperature dispersion using polarized interference" [J. Appl. Phys. 81, 425 (1997); 77, 5942 (1995)], J APPL PHYS, 87(9), 2000, pp. 4638-4639
Fischer and Ohmer [J. Appl. Phys. 81, 425 (1997); 77, 5942 (1995)] could no
t explain the paradox concerning the anomalously low phase matching angle f
or second harmonic generation of CO2 laser radiation in ZnGeP2 crystal by t
heir measured birefringence and its temperature dependence. Based on their
measured birefringence and its temperature dispersion we have shown that a
temperature rise of such crystal by 150 degrees C or so, is enough to expla
in this anomaly. (C) 2000 American Institute of Physics. [S0021- 8979(00)07
309-6].