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Hongfei Liu

Bio: Hongfei Liu is an academic researcher from Hunan University. The author has contributed to research in topics: Terahertz radiation & Absorption (acoustics). The author has an hindex of 5, co-authored 7 publications receiving 129 citations.

Papers
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Journal ArticleDOI
TL;DR: The proposed photonic quasi-crystal fiber with high birefringence maintains a high nonlinear coefficient and low confinement loss, which is two orders of magnitude larger than that of the conventional polarization-maintaining fibers and hardly affected by the incident wavelength.
Abstract: A photonic quasi-crystal fiber (PQF) with high birefringence is proposed. A dodecagonal Stampfli quasi-periodic lattice of air holes constitutes the cladding of the PQF. The PQF maintains the properties of high birefringence and single-mode operation regime in a wide wavelength range from 1.2 to 2.0 μm by optimizing the size of the air holes around the core of the PQF. A birefringence with 3.86×10−2 can be obtained at 1.31 and 1.55 μm optical telecommunication windows. The birefringence is of the order of 10−2, which is two orders of magnitude larger than that of the conventional polarization-maintaining fibers and hardly affected by the incident wavelength. The proposed PQF also maintains a high nonlinear coefficient and low confinement loss. Our structure and simulation results are expected to provide a valuable reference and basic data to relative fabrication and experiments.

40 citations

Journal ArticleDOI
01 May 2016-Optik
TL;DR: In this paper, a photonic quasi-crystal fiber (PQF) with a near zero flattened dispersion in the 1450-1650-nm optical telecommunication window is proposed.

36 citations

Journal ArticleDOI
TL;DR: In this paper, a high-birefringence photonic quasi-crystal fiber (HB-PQF) based on SiO2 was proposed and the relation- ships between bireringence and structure parameters were investigated by finite difference beam propagation method, and with the optimization of fiber structure parameters, the birerringence was 1.4207 × 10 −2, which is two orders of magnitude higher than the normally used fiber when the wavelength is 1.55 μm.
Abstract: 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)

27 citations

Journal ArticleDOI
TL;DR: In this article, a decagonal photonic quasi-crystal (PQC) flat lens was designed to turn an incident terahertz (THz) plane wave into a hollow beam easily and flexibly.
Abstract: 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

17 citations

Journal ArticleDOI
TL;DR: In this article, the effects of material/structure parameters of photonic crystal (PhC) parallel waveguides on the coupling length are investigated, and it is shown that increasing the effective relative permittivity of the PhC leads to a downward shift of the photonic bandgap and a variation of coupling length.
Abstract: In this Letter, the effects of material/structure parameters of photonic crystal (PhC) parallel waveguides on the coupling length are investigated. The results show that, increasing the effective relative permittivity of the PhC leads to a downward shift of the photonic bandgap and a variation of the coupling length. A compact PhC 1.31/1.55 μm wavelength division multiplexer (WDM)/demultiplexer with simple structure is proposed, where the output power ratios are more than 24 dB. This WDM can multiplex/demultiplex other light waves efficiently.

15 citations


Cited by
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Journal ArticleDOI
Exian Liu1, Wei Tan1, Bei Yan1, Jianlan Xie1, Rui Ge1, Jianjun Liu1 
TL;DR: 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.
Abstract: 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.

96 citations

Journal ArticleDOI
TL;DR: A D-shaped photonic quasi-crystal fiber (PQF) sensor based on surface plasmon resonance is proposed for refractive index (RI) sensing that realizes the high-sensitivity sensing in the near-infrared band.
Abstract: 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.

75 citations

Journal ArticleDOI
TL;DR: In this paper, a photonic crystal fiber based on a modified hexagonal structure has been discussed and demonstrated modal analysis precisely, which shows higher sensitivity as a chemical sensor for lower refractive index chemicals such as Water, Ethanol and Benzene.
Abstract: 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.

71 citations

Journal ArticleDOI
TL;DR: In this article, a novel polarization filter based on a sunflower-type photonic quasi-crystal fiber (PQF) is proposed, which 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.
Abstract: 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.

69 citations

Journal ArticleDOI
TL;DR: In this article, the double-cladding structure dependence of guiding characteristics in six-fold symmetric photonic quasi-crystal fiber (PQF) is investigated, and three PQFs featuring one, two and three inner air holes are considered.

68 citations