We mainly investigate the forward Brillouin scattering in photonic crystal fiber. Recently we fabricate a PCF with phononic band gap. And the frequency of the core resoant mode just lies inside the bandgap. We have measured the frequency of the acoustic core mode. And now we try to calculate its acoustic displacement field with COMSOL. And the set the estimited eigen frequency based on our experiment. But we can not get the right eigen acoustic mode. The core area has very small displacement. However the veins near the core connecting the core and the cladding show large displacement. We do not know the reason. Why?
↧