An electro-optic tunable single and multi-channel optical filter based on one-dimensional defective photonic crystal (1DDPC) structure is proposed. A couple of externally tunable defects in arrangement of (AB)5D1(BA)D2(BA)5, where A and B are dielectric materials, D1 and D2 are the tunable defects are used. The defects are composed of the ferroelectric LiNbO3 crystals and two pairs of thin Ag layers to make the voltage connections. With this arrangement it is possible to apply different external biases that facilitate the tunability and even more adjustability of the channel frequencies. Depending on the thickness of defect layers, a single or multi resonant peak can be induced inside the photonic band gap which can be employed to filter channels. About 37 nm (46 nm) of blue shift for 300 V and 37 nm (37 nm) of red shift for -300 V biases are observed without (and with) loss incorporation. An important and notable effect that happened was the dispersion loss of the structure due to metal layers is compensated by the negative biases. Our proposed structure can be good candidate to design an externally tunable optical filter and a voltage sensor with potential applications in all-optical signal processing and information communications fields. پرونده مقاله

In this paper, we employed the attenuated total reflection (ATR) technique to theoretically and experimentally measure the thickness of metal thin films and compare together them. The computations of the present study were carried out using characteristics matrix method. The ATR technique is based on the excitation of surface polaritons. In the ATR spectra polariton, the surface polaritons manifest themselves as sharp reflectivity minima. We used this minimum to measure the thickness of a silver layer coated on the surface of a prism. We observed that the measured value has a good agreement with the real thickness of the layer. پرونده مقاله

In this article, the adjustability of the multi-channel optical filter including magnetized materials and uniaxial anisotropic metamaterials in the three-dimensional one-dimensional photonic crystal structure in the GHz frequency range has been theoretically analyzed and designed. It is shown that resonant peaks in the transmission spectrum can be created in the presented structure without adding a defect layer, in the absence and presence of an external magnetic field. Therefore, the presented ternary periodic structure can act as an adjustable multi-channel filter using the transmission spectrum of the photonic crystal. Also, the characteristics of the transmission spectrum of the assumed structure can be manipulated by applying an external magnetic field, so that the frequency of the channels can be red-shifted or blue-shifted depending on the direction of the applied magnetic field. In addition, the effect of the number of periods of the structure, the optical axis angle of anisotropic metamaterials (φ) and the incident light radiation angle (θ) on the filtering characteristics of the channels in both TE and TM polarizations have been numerically investigated پرونده مقاله

Abstract: The current research is aimed to investigate the alterations of its optical
features of novel adjustable three color narrowband optical filters, which comprise of
blue, green and red light. A narrowband adjustable transmission optical filters according
to dielectric- ferroelectric heterostructures photonic structures are designed using the
transfer-matrix method (TMM). The dependence of the ferroelectric refractive index on
the external applied voltage is considered in our investigations. The transmission spectra
of the designed hetrostructures with the most valuable parameters, like repeat cycle
counts number of PCs, external electric field, and incident angle for both TE and TM
polarizations are numerically investigated. The results show that the transmission peaks
of three color filter shift toward the shorter wavelength by increasing the incident angle
for both polarization. Also, adjustability of the optical features of the proposed
hetrostructures crystals external applied electric field is investigated .Therefore, these
calculated results reveal an innovative idea for designing the tunable trichromatic filter
and display applicationsthis. پرونده مقاله