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We design a crystal photonic fiber (PCF) polarization filter with asymmetric structure and two large air-holes coated with gold film. The influence of the thickness of metal layers and the diameter of large air-holes on the filtering characteristic is investigated using finite element method (FEM). In calculations, the sixth and the third order surface plasma modes (SPM) are presented. The resonance positions are well separated by the asymmetry of the structure in vertical direction. The loss of unwanted polarization is 829 and 1267 times than that of wanted polarization at 1.48 and 1.55 μm respectively. When the fiber length is 3 mm, the crosstalk is 1055 dB and 927 dB for 1.48 and 1.55 μm. The bandwidth with crosstalk better than 20 dB can reach to 1000 nm, covering almost all communication band. What’s more, gold excitation of SPR and silver excitation of SPR are compared and studied. [ABSTRACT FROM AUTHOR]

One-dimensional photonic crystal (1D PC) filters with one defect layer are investigated at visible frequencies both theoretically and experimentally. 1D PC filters containing one Al 2 O 3 or TiO 2 defect layer are fabricated by pulsed laser deposition. The optical properties of the filters, including the transmittance and the resonance wavelength, are numerically calculated by using the transfer matrix method. Our results show that the defect layer with the lower refractive index is more suitable for the filters. Both blue- and red- shifts of the filter resonance are observed, depending on the thickness of the defect layer. We also find that the resonance may disappear as the number of periods in the filter increases (with the optical thickness of the defect layer fixed at 3/2 λ . [ABSTRACT FROM AUTHOR]

Abstract: A new type temperature-insensitive quartz filter is presented in this paper, which is composed of three polarizers, a quartz birefringent crystal and a quartz rotation crystal. Based on the principle that the fluctuations of the quartz birefringence and specific rotation have an opposite trend with the temperature change, the temperature effect on output center wavelength of this new type quartz filter is investigated in detail theoretically and experimentally. The theoretical and experimental results show that this new type quartz filter is indeed insensitive to temperature change. It will have a certain application in the stability output of optical filter when temperature change as we believe. [Copyright &y& Elsevier]

Abstract: A method of photonic crystal filter using resonant cavities in two dimensional structures suitable for WDM and DWDM communication applications is proposed. For the design of the structure, movement of defects as resonant cavities is utilized. Tuning the desired wavelengths with characteristics according to ITU-T standard is shown. By changing characteristics such as radius of defects, distance of them from each other and location of defects, a compact optical filter proper for optical integrated circuits is proposed. Also, the combined effect of introduction of variable radius of defects and distances of them from each other, resulted interesting characteristics. [Copyright &y& Elsevier]

Abstract: Light propagation characteristics of the channel filters based on the two-dimensional photonic crystals with elliptic defects are studied by the finite-difference time-domain method. The two-dimensional photonic crystal consists of a triangular array of air holes immersed in the silicon background. Shape alteration of the air hole from a circle to an ellipse offers a powerful approach to engineer the resonant frequency of channel filters. And the resonant frequency can be flexibly adjusted only by changing the orientation angle of the elliptic holes. A six-channel drop filters based on the elliptic holes with different obliquities is designed. Connected with the active optical device, above structure can be employed as a kind of frequency division and direction separation device, which is suitable in the complicated optical circuits. [Copyright &y& Elsevier]

Abstract: Off-axis transmission spectrum of quartz rotation filter is studied in this paper in detail through numerical simulation and experiment research, we find the central wavelength, band width and amplitude of output light will all change when the quartz rotation filter is rotated with a tilted angle, the central wavelength will change to a longer wavelength, band width and amplitude will decrease as the tilted angle increase. These results will be helpful to further explore the transmission character of quartz birefringence, rotation filter and relative applications, as we believe. [Copyright &y& Elsevier]

Abstract: Transmission characteristics of one-dimensional (1D) photonic crystals (PCs) heterostructures containing defective are studied using the transfer matrix method. The key is to search the best combination style for different 1D PCs to form heterostructures. It is shown that the non-transmission range over near ultraviolet and visible range can be substantially enlarged and the phenomenon of narrow band PC filter in near ultraviolet can be realized by adjusting the repeat cycle counts of various photonic crystals. The theoretical results on multiple heterostructures containing TiO2/SiO2 multilayer films are presented. With a perfect omni-directional and high peak transmission filters for TE modes, this structure opens a promising way to fabricate ultra-narrow band PC filters with wide non-transmission range in near ultraviolet and visible range. [Copyright &y& Elsevier]

In this paper, a dual-polarizated photonic crystal fiber filter (PCF) based on surface plasmon resonance (SPR) was proposed. Its polarization characteristics were numerically researched by finite element method (FEM). The results indicate that the polarization filtering of the filter be able to fulfill in dual communication bands of 1310 and 1550 nm. The confinement loss reaches 80,711.4 dB/m for the x polarization core mode at the wavelength of 1310 nm, while 46,614.5 dB/m for the y polarization core mode at the wavelength of 1550 nm. When the length of PCF is 2.5 mm, the extinction ratios of x and y polarization core modes can achieve 1705.27 and − 883.46 dB, respectively. For the communication windows of 1310 and 1550 nm, the filtering bandwidths can reach to 390 and 350 nm, respectively. These excellent characteristics are beneficial to the design and manufacture of filter devices. • A PCF dual windows polarization filter based on SPR is proposed. The square arrangement of air holes is easy to prepare. • The losses of the filter at dual windows can reach 80,711.4 dB/m and 46,614.5 dB/m. • When L PCF = 2.5 mm, the ER of the two orthogonal modes can reach 1705.27 and − 883.46 dB. The bandwidth can reach 390 nm and 350 nm. [ABSTRACT FROM AUTHOR]

We theoretically investigate and discuss a mechanically tunable ultra-narrowband optical filter based on a one dimensional quasi-periodic photonic crystal (QPPC) and an on-chip integrated MEMS actuator. High reliability, high wavelength tunability, integration capability and wide spectral shift are several advantages of the proposed filter. The optical response of the filter in the telecommunication region is obtained using a finite-difference-time domain (FDTD) method. The functional characteristics of the proposed filter according to the simulation results are as follows: a wavelength sensitivity of 0.323 nm/nm, FWHM of 5 nm, a spectral range of 34 nm, resonance mode quality factor of 310%, and 50% average transmission efficiency. Moreover, this device can be employed as the basic block of many devices such as displacement sensors, inertial sensors, ultra-narrowband tunable light absorbers, optical modulators and so on. [ABSTRACT FROM AUTHOR]

In this work, based on the use of ITO as a defect, we study the infrared defect mode in defective photonic crystal made of SiO 2 and InP. Due to the dispersion in the dielectric function of ITO, it is found that the defect mode is sensitive to the ITO thickness. The defect frequency is shown to be blue-shifted as the thickness of ITO decreases. In the angular dependence of defect mode, it is seen that the defect frequency is also blue-shifted when the angle of incidence increases for both TE and TM polarizations. However, the shifting feature is appeared to be nearly polarization-independent. The shift in the defect frequency enables us to employ ITO as a tunable agent in order to design a tunable photonic crystal filter in the infrared region. [ABSTRACT FROM AUTHOR]

Abstract: The effect of temperature on the spectrum characteristic of the liquid crystal filter in the region of visible light was investigated theoretically and experimentally in detail. The conclusion shows that with the increasing temperature, the center wavelength of the filter will shift toward the short wavelength, and the center wavelength of the filter will shift toward long wavelength as the temperature decreases. The result of numerical simulation is in excellent agreement with the experiment result. In addition, the experiment results indicate that with the increasing temperature and reducing wavelength the transmittance of liquid crystal filter will reduce. According to the above conclusion we propose a new structure for maintaining a stable central wavelength output of the liquid crystal filter with the changing temperature, and it does not require temperature control equipment, is easy to operate, and has no need to look for special temperature coefficient birefringence, etc. This structure may find a certain application for liquid crystal filter as we believe, particularly, in the condition of different environment temperature. [Copyright &y& Elsevier]