Direct measurement of infrared photo-elastic constants of silicon

The elasto-optic constants of single-crystal silicon were determined at 3.39μ, through measurement of the diffraction grating and transduction efficiency of an ultrasonic traveling-wave modulation device operating at 30 MHz. The values of elasto-optic constants found were
P_{11} = 0.081, P_{12} = 0.010, P_{44} = 0.075
.