investigation on the optical transition of hexagonal boron nitride

We study the relationship between the optical transition of hexagonal boron nitride and the direction of its optical axis. the results show that the optical transition can be tunable by adjusting its optical axis; therefore, it provides us an active way to control the optical transition. the reflection and transmission near the optical transition have been investigated and the results show that hexagonal boron nitride can be tuned from good reflector to transmitter or reverse. the results in this paper help us better understand the optical transition of hexagonal boron nitride.