Parameters
n: refraction index
Fa: optimal acoustic frequency
la: acoustic wavelength
va: velocity of the acoustic wave
L: interaction length
l: interaction width
M: merit factor
P: acoustic power
lam: optical wavelength
dFa: shift of the acoustic wave frequency
T0: diffraction efficiency at the optimal acoustic frequency
TdFa: diffraction efficiency at an acoustic frequency shifted of dFa from the optimal frequency
effLoss: relative loss of diffraction efficiency caused by the acoustic frequency shift
