In this work, an octagonal Penrose-type photonic quasi-crystal fiber (PQF) with dual-cladding is proposed. By optimizing three geometric degrees of freedom, the PQF exhibits ultra-flattened near-zero dispersion of 0.014±0.293  ps/nm/km, ultra-low order confinement loss of 10−4  dB/km, and large effective mode area of over 16.2  μm2 in a broadband of wavelength from 1.27 to 1.67 μm, covering almost all optical communication bands. At the common communication wavelength 1.55 μm, completely opposite trends of the dispersion and the confinement loss varying with the air-filling factor in the inner cladding are demonstrated. In addition, the robustness of optical properties including dispersion, confinement loss, and effective mode area in this PQF is discussed, assuming a deviation ±3% of all air holes.

Broadband ultra-flattened dispersion, ultra-low confinement loss and large effective mode area in an octagonal photonic quasi-crystal fiber.

A D-shaped photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance is proposed for refractive index (RI) sensing. The influences of the width of the gold film, the diameter of the air holes, and the thickness of the gold film on the sensing performance are analyzed. When the RI of a liquid analyte gradually increases from 1.415 to 1.427, the average sensitivity is calculated as 10,250 nm/RIU, and the maximum sensitivity is up to 34,000 nm/RIU, which realizes the high-sensitivity sensing in the near-infrared band. The D-shaped PQF sensor proposed has great application potential in the detection of biochemical analytes and provides a new way to improve the sensing performance.

Refractive index sensing characteristics in a D-shaped photonic quasi-crystal fiber sensor based on surface plasmon resonance.

In this paper, a highly sensible photonic crystal fiber based on a modified hexagonal structure has mentioned and demonstrated modal analysis precisely. Numerical investigation of the proposed fiber is rigorously computed using full vector finite element method (FV-FEM) with anisotropic perfect match layers. Liquid analytes are used here to infiltrate fiber core. Relative sensitivity is numerically investigated and optimized by varying the different parameters of the proposed structure at a wider wavelength regime 1.0–1.7 μm within IR region. The proposed simple structural PCF shows higher sensitivity as a chemical sensor for lower refractive index chemicals such as Water, Ethanol and Benzene. Moreover, some essential properties such as confinement loss, V parameter, spot size, beam divergence, and nonlinearity are also represented distinctly. The proposed PCF gains higher sensitivity of 53.22%, 48.19% and 55.56% for Ethanol, Water and Benzene respectively at 1.33 μm wavelength with lower confinement loss. Above result reveals that proposed fiber is capable to provide potential impact in telecommunications, chemical sensing as well as bio-sensing also.

Liquid-infiltrated photonic crystal fiber for sensing purpose: Design and analysis

A novel polarization filter based on a sunflower-type photonic quasi-crystal fiber (PQF) is proposed in this paper. We also discuss different methods to tune the filter wavelength. The proposed filter can efficiently produce polarized light with visible wavelengths by using the resonance between the second-order surface plasmon polariton mode and the core mode of the PQF. The filtered wavelength can be tuned between 0.55 µm and 0.68 µm by adjusting the thickness of the gold film. When the thickness of the gold film is 25.3 nm, the resonance loss in the y-polarized direction reaches 11707 dB m−1 for a wavelength of 0.6326 µm, and the full width at half maximum is only 5 nm. Due to the flexible design and absence of both polarization coupling and polarization dispersion, this polarization filter can be used in devices that require narrow-band filtering.

https://iopscience.iop.org/article/10.1088/1361-6463/aab4ce/pdf

Polarization filtering in the visible wavelength range using surface plasmon resonance and a sunflower-type photonic quasi-crystal fiber

Double-cladding structure dependence of guiding characteristics in six-fold symmetric photonic quasi-crystal fiber

Dispersion properties of a photonic quasi-crystal fiber with double cladding air holes

A high-birefringence photonic quasi-crystal fiber (HB-PQF) based on SiO2 is proposed. The relation- ships between birefringence and structure parameters and between beat length and structure parameters are researched by finite difference beam propagation method. With the optimization of fiber structure parameters, the birefringence is 1.4207 × 10 −2 , which is two orders of magnitude higher than the normally used fiber when the wavelength is 1.55 μm. The radius of the fiber is 6.5 μm. The HB-PQF in a communication sensor will have important application prospects. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE) (DOI: 10.1117/1.OE.55.3.036101)

Photonic quasi-crystal fiber with high birefringence

We have designed a decagonal photonic quasi-crystal (PQC) flat lens, which turns an incident terahertz (THz) plane wave into a hollow beam easily and flexibly The features of the THz hollow beam can be controlled by varying the parameters of a point defect in the center of the lens, ie, the PQC flat lens can be used as a flexible tool for THz optical captivity or optical tweezer The results showing that an airy disk, whose mean beam width is similar to the incident wavelength and power-in-the-bucket (PIB) is more than 96%, can be generated in the far field

https://iopscience.iop.org/article/10.7567/APEX.9.062003/pdf

Generation of terahertz hollow beams by a photonic quasi-crystal flat lens

The invention discloses a novel high-birefringence photonic quasicrystal fiber, a background material is SiO2, scatters of the entire structure are arranged in a tenfold Penrose type photonic quasicrystal structure, the lattice constant is lambda, and diameters of round air holes of a wrapping layer are d3 and d4, wherein d3 derives from the scatters of the third layer to the fifth layer of the tenfold Penrose type photonic quasicrystal structure, and d4 derives from the scatters of the sixth layer to the ninth layer of the tenfold Penrose type photonic quasicrystal structure; and six roundly air holes are introduced into a core region, diameters of four round air holes at upper and lower sides are d1 and derive from four scatters of the second layer of the tenfold Penrose type photonic quasicrystal structure which are close to +/- Y axis, and diameters of two round air holes at left and right sides are d2 and derive from two scatters of the third layer of the tenfold Penrose type photonic quasicrystal structure on +/- X axis; and to enhance asymmetry so as to improve birefringence, two round air holes whose diameters are d5 are introduced to positions of 1.3*lambda on the +/-Y axis. The novel high-birefringence photonic quasicrystal fiber provided by the invention has the advantages that mode field energy distribution is concentrated and limitation of an existing technological level to fiber preparation is reduced.

Novel high-birefringence photonic quasicrystal fiber

The invention discloses an efficient photonic crystal 1.31/1.55 [mu]m wavelength division multiplexer. The refractive index distribution of the wavelength division multiplexer is a dielectric cylinder type, the dielectric cylinders of the whole structure are arranged in a triangular lattice structure, the lattice constant a=0.6[mu]m, the radius of the dielectric cylinder r=0.12[mu]m, the refractive index of material is 2.95, a semiconductor material indium nitride is doped corresponding to a III-V group, 29 or 30 dielectric cylinders are contained in a length direction, and 14 dielectric cylinders are contained in a width direction, the dielectric cylinders of the last but five rows are removed and a waveguide I is introduced; the dielectric cylinders in a middle part of the sixth row are removed, at least four dielectric cylinders are left at each of two sides, and a waveguide II parallel to the waveguide I is formed and led out at the right end; two rows of dielectric cylinders separate the waveguide I and the waveguide II and form an interaction area, and the two waveguides form a direction coupling waveguide structure. The wavelength division multiplexer has the advantages that the structure is simple, the performance is good, the size facilitates integration, etc., and has relatively good application prospects in communication integrated optical circuits.

Jianjun Liu

Papers

Dispersion properties of a photonic quasi-crystal fiber with double cladding air holes

Photonic quasi-crystal fiber with high birefringence

Generation of terahertz hollow beams by a photonic quasi-crystal flat lens

Novel high-birefringence photonic quasicrystal fiber

Efficient photonic crystal 1.31/1.55 [mu]m wavelength division multiplexer