We demonstrate a quasi-periodic structure exhibiting multiple photonic band gaps (PBGs) based on submicron-period poled lithium niobate (LN).The structure consists of two building blocks,each containing a pair of antiparallel poled domains,arranged as a Fibonacci sequence.The gap wavelengths are analyzed with the Fibonacci sequence parameters such as the quasiperiodic indices and the average lattice parameter.The transmission properties are investigated by a traditional 4×4 matrix method.It has also been proved that the gap depth can be tuned by the lengths of poled domains.
The response time and transmittivity of the magnetic fluid(MF)for different concentrations at room temperature were investigated in this letter.The volume fraction of the investigated sample ranged from 0.44% to 6.47%.It was found that the transmittivity decreased with increasing concentration under a given magnetic field,and the evolution time was changed with different concentrations.Moreover,the light intensity decreased rapidly at the beginning and then became stable when the magnetic field was applied.
