We demonstrate a quasi-periodic structure exhibiting multiple photonic band gaps （PBGs） based on sub- micron-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.
Self-focusing effect via Kerr nonlinearity is observed in periodically poled lithium niobate （PPLN） waveguide arrays formed by electro-optic effect. Voltage-control method is demonstrated to control the focusing and diffraction of light. Theoretical simulation results show good agreement with experimental results.
The liquid-core fiber with relatively high refractive index difference between the core and cladding is proven to be bending insensitive. The single mode condition and bending loss of the fiber with a mixture of toluene and chloroform as its core material are studied. The results show that the bending loss of this fiber is not only much smaller than the conventional silica single mode fiber but also can be tuned by the temperature and liquid mixture ratio. This kind of fiber may find its potential applications in all-optical network.
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.
