Realization of an optical demultiplexor using the combination of filter and finite difference time domain approach

The present paper presents a simple theoretical model of optical demultiplexerusing the combination of filters and finite difference time domain technique. Though some works related to similar type of research is found in literature, the newness of proposed work manipulates with finite difference time domain method (FDTD) where all previous work deal with plane wave expansion method. In this article filter is accomplished by the combination of three layers of silicon and air material which represents as 1D photonic crystal structure. The photonic band gap of above said structure play a key role to obtain the allowance or disallowance of signal pertaining to structure parameter. Simulation results reveal that the structure parameter of the crystal including thickness of odd and even layers play a vital role in designing of the demultiplexor. For example filter having thickness of odd layer (silicon) of 950 nm and even layer (air) of 50 nm permits the wavelength 1290 nm, and thickness of odd layer of 877 nm and even layer of 123 nm allows wavelength,1310 nm. Also thickness of odd layer of 860 nm and even layer of 140 nm permits the signal of 1330 nm.