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Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes
Optical Materials 73 (2017) 638e641
Contents lists available at ScienceDirect
Optical Materials journal homepage: www.elsevier.com/locate/optmat
Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes Yunyan Zhao*, Shuguang Li, Qiang Liu, Xinyu Wang Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 21 May 2017 Received in revised form 17 August 2017 Accepted 18 August 2017
In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 mm, the crosstalk in the wavelength range from 1.4 mm to 1.9 mm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter. © 2017 Published by Elsevier B.V.
Keywords: Photonic crystal fiber Polarization filter Surface plasmon resonance Gold-coated
1. Introduction As a new communication technology, compared with the traditional optical fiber, photonic crystal fibers (PCFs) [1e3] have many advantages. As time passed, the researchers found that some materials can be applied to optical fiber communication technology, such as liquids [4], liquid crystals [5], oil [6], or metals [7]. The addition of a certain amount of material to the fiber affects its transmission characteristics [8e11]. This attracted the interest of many researchers. More recently, gold-filled and gold-coated photonic crystal fibers have been considered. The results show that the use of metal materials can produce photonic crystal fibers with better transmission performance. After adding the metal material, the surface of the metal will form the surface plasmon polaritons (SPP). In addition, when phase matching conditions between core mode and SPP mode are met, coupling resonance phenomenon will occur at a certain wavelength. Nowadays, many researchers have done a lot of novel designs on this basis. Nagasaki et al. [12] have described that the surface plasmon resonance effect can produce loss peak wavelengths. On the basis of the plasma resonance effect, Xue and Li [13]
* Corresponding author. E-mail address: [email protected] (Y. Zhao). http://dx.doi.org/10.1016/j.optmat.2017.08.029 0925-3467/© 2017 Published by Elsevier B.V.
designed a photonic crystal fiber with selective addition of gold and filled liquid whose loss in the y polarization direction reached 508 dB/cm. Wang proposed a quadrilateral coated metallic photonic crystal fiber which can achieve a resonance strength of 720 dB/cm in the y-polarized direction [14]. The results show that the gold-coated photonic crystal fiber has better filtering effect than the gold-filled photonic crystal fiber. In this paper, we have designed a new type of photonic crystal fiber with elliptical air holes and selectively plated gold to the air holes. Simul-ation results show that, compared with [12e14], the PCF has better polari-zation filter characteristics and higher cross talk (CT)at the communication wavelength. At the same time, we also compared the characteristics of the PCF between gold-coated and gold-filled. 2. Structure and theroretical principle The cross section of the PCF polarized filter with elliptical air holes is shown in Fig. 1. Here, the core is formed by removing an air hole in the center. It has four large air holes and two elliptical air holes around it. At the same time, the whole structure is formed by rotating the quadrilateral by 45 . In order to form the surface plasmon effect, we have coated gold on the upper and lower air holes of the core, respectively. As shown in Fig. 1, d1 and D denote the diameter and lattice spacing of the clad air holes, respectively.
Y. Zhao et al. / Optical Materials 73 (2017) 638e641
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Fig. 2. PML and scattering boundary conditions.
Fig. 1. Cross section of the proposed photonic crystal fiber filter.
In addition, the diameter of the four large holes is d2, where a and b are the minor axis length and the major axis length of the elliptical hole, respectively. For this structure, the parameters d1, d2, a and b are fixed to 0.8 mm, 0.8 mm, 0.5 mm and 1.0 mm, respectively. The lattice pitch is D ¼ 2 mm and the thickness of the gold layer d is fixed to 20 nm. We use pure silica as the background material. Its chromatic dispersion is calculated by the Sellmeier equation [15]. The refractive index of air is 1. The permittivity of the gold is calculated by the DrudeLorentz model [16]:
εm ¼ ε∞
u2D
uðu jlDÞ
Dε,U2L u2 U2L jGL u
where ε∞ is the high-frequency permittivity, ε∞ ¼ 5.9673; Dε ¼ 1.09, UL and GL are the frequency and the spectral width of the Lorentz oscillator, respectively. u is the angular frequency of guided light, while uD and gD represent the plasma freq-uency and damping frequency. Here, uD/2p ¼ 2113.6 TH Z; gD/2p ¼ 15.92 THZ; UL/2p ¼ 650.07 THZ; GL/2p ¼ 104.86 THZ. As an important parameter of polarizati-on filters, the mode loss of the fiber can be expressed as
L ¼ 8:686
2p
l
Imðneff Þ 104
There are two important parameters in the above equation: l and Im (neff), which represent the wavelength of the incident light and the imaginary part of the effective refractive index of the fiber core [17], and the units correspond to microns and dB/cm, respectively. In the whole process of simulation using the finite element method, we apply the perfectly matched layer (PML) and the scattering boundary conditions (see Fig. 2). When the phase matching condition is reached, the core mode can be strongly coupled with the SPP mode.
3. Numerical results and analysis Fig. 3 shows the fiber core mode and the surface plasmon
polaritons (SPP) mode field distribution. Since we selectively plated the two air holes with gold film, the surface plasmon resonance effect was produced. In this way, the two modes mentioned above will be strongly coupled at a certain wavelength, and there will be greater energy loss in one of the polarization directions of this wavelength, so that it can be used as a polarization filter. When the structural parameters of the fiber are optimized, the peak value of the loss will appear in a certain direction of polarization due to the asymmetry of the structure, so as to achieve a good polarization filtering effect at this wavelength. Fig. 4 shows the loss dispersion profile for the optimized structural configuration. At this time, d1, d2, a and b are fixed at 0.8 mm, 0.8 mm, 0.5 mm and 1.0 mm and the thickness of the gold layer is fixed at 20 nm. It can be clearly seen from the figure that the core mode and the SPP mode of the Y-direction of the 1550 nm wavelength are strongly coupled so that the peak of the loss is much larger than that in the x-direction, and the fiber has a good polarization filtering effect at 1550 nm. Another important parameter of the photonic crystal fiber filter is crosstalk (CT), which can represent the filtering effect of the filter, and it can be defined as [18]
CT ¼ 20lgfexp½ða2 a1ÞLg where a1 and a2 represent the loss in the X and Y directions, whereas L represents the fiber length. Fig. 5 shows the relationship between crosstalk and fiber length. As can be seen from the figure, with the increase in wavelength, CT also showed a certain change trend. When the length of the fiber exceeds 100 mm, in the 1.4e1.9 mm wavelength range, CT are more than 20 dB, which means that the fiber has a good filtering effect and can be used to make the filter. As we know, when the structure of the optical fiber changes, some of its transmission characteristics will change accordingly. Therefore, if we analyze the variation of the influence of parameters on the transmission characteristics, we can have some guiding significance for the manufacture of optical fiber. So we have a simple analysis on some structural parameters, which may have some impact on the transmission characteristics of this fiber. In this paper, we focus on these two parameters: air holes diameter, gold film thickness and the size of the elliptical air hole. Next, we discuss the effect of the four orifices surrounding the core on the fiber filter effect. As shown in Fig. 6, in this paper, when the other parameters remain constant, we make the gradient of d2 from 0.6 mm to 1.1 mm. It can be seen in this band that the loss formant has red shift phenomenon in the y-polarized direction,
640
Y. Zhao et al. / Optical Materials 73 (2017) 638e641
Fig. 3. The electric field distributions of (a)x-polarized (b)y-polarized core mode and (c)x-polarized (d)y-polarized SPP mode.
Fig. 4. The dispersion relation of the optical fiber core mode and SPP mode.
Fig. 6. The variations of the resonance peak for different values of d2.
short axes of the ellipse to analyze its effect on the transmission characteristics. As can be seen from Fig. 7, when we make a series of changes in the size of the ellipse, the loss peak will also change, so as long as we make the appropriate value to the elliptical air hole size, then it will have some certain influence on the optimize structure. In this way, changing the elliptical air hole can be used as
Fig. 5. The peak value variations of the CT for different fiber lengths L ¼ 100 mm (black curve), L ¼ 200 mm (red curve), L ¼ 300 mm (blue curve) and L ¼ 400 mm (green curve). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
which means moving toward the long-wave direction while the loss in the x-polarized direction increases as d2 changes. Again, we take into account the effect of the size of the ellipse. In this section, we try to make a corresponding change in the long and
Fig. 7. The variations of the resonance peak for different values of a and b.
Y. Zhao et al. / Optical Materials 73 (2017) 638e641
641
the future for the manufacturing of optical fiber filters. Acknowledgments This work was supported by the National Natural Science Foundation of China (Grant No. 61475134, 61505175) and Key Program of the Natural Science Foundation of Hebei Province (Grant No. F2017203193). References
Fig. 8. The variations of the resonance peak for different thicknesses of the gold film.
an optimization means to change the transmission properties of photonic crystal fibers. Finally, let us see if the thickness of the metal layer to change, the performance of the fiber will be how to change. As in the above case, we use the principle of a single variable, gradually change the thickness of the metal layer, so that it changes from 10 nm to 30 nm. It is clearly seen from Fig. 8 that, along with the change of the metal layer, the y direction of the resonance peak occurs. Obviously, the thickness of the metal layer on the performance of fiber is very significant, so we change the thickness of the metal layer, you can according to the law of change to create what we want. At the same time, we also compared the coated gold film and filled with gold wire. Obviously, compared with the addition of wire, the filtering effect of the coated photonic crystal is better. Therefore, the coated gold film is also a new method to change the performance characteristics of the photonic crystal fiber. 4. Conclusion In this work, we introduce a new type of photonic crystal fiber, and use the finite element method to analyze and compare it. The resonance strength and the impact of the structural parameters of the photonic crystal fiber on the polarization filter characteristics are studied. The numerical results show that the resonance intensity in the y-direction can reach 906.9 dB/cm at the wavelength of 1550 nm. When the fiber length is greater than 100 nm, its crosstalk can be well over 20 dB. Therefore, it can be considered in
[1] P. Russell, Photonic crystal fibers, J. Appl. Phys. Rev. 299 (2003) 358e362. [2] K. Saitoh, M. Koshiba, Photonic bandgap fibers with high birefringence, J. IEEE Phot. Technol. Lett. 4 (2002) 1291e1293. [3] K. Tajima, J. Zhou, K. Nakajima, K. Sato, Ultralow loss and long length photonic crystal fiber, J. Lightw. Technol. 22 (2004) 7e10. [4] T. Matsui, J. Zhou, K. Nakajima, S. Izumi, Dispersion-flattened photonic crystal fiber with large effective area and low confinement loss, J. Lightw. Technol. 23 (2005) 4178e4183. [5] J.H. Liou, S.S. Huang, C.P. Yu, Loss-reduced highly birefringent selectively liquid-filled photonic crystal fibers, J. Opt. Commun. 283 (2010) 971e974. [6] Y. Geng, X. Li, X. Tan, Y. Deng, X. Hong, Compact and ultrasensitive temperature sensor with a fully liquid filled photonic crystal fiber mach-zehnder interferometer, J. IEEE Sens. 14 (2004) 167e170. [7] H.K. Tyagi, M.A. Schmidt, L. Prill Sempere, P. St, J. Russell, Optical properties of photonic crystal fiber with integral micron-sized Ge wire, J. Opt. Express 16 (2008) 17227e17236. [8] D.J. Won, M.O. Ramirez, H. Kang, V. Gopalan, N.F. Baril, J. Calkins, J.V. Badding, P.J.A. Sazio, All-optical modulation of laser light in amorphous silicon-filled microstructured optical fibers, J. Appl. Phys. Lett. 91 (2007) 161112. [9] M. Chen, R. Yu, A. Zhao, Polarization properties of rectangular lattice photonic crystal fibers, J. Opt. Commun. 241 (2004) 365e370. [10] H. Zhao, M. Chen, G. Li, Temperature dependence of the PER in PM-PCF Coil. Chi, J. Opt. Lett. 10 (2012) 17e19. [11] Y. Wang, M. Alharbi, T.D. Bradley, C. Fourcade-Dutin, Hollow-core photonic crystal fibre for high power laser beam delivery, J. High Power Laser Sci. Eng. 1 (2013) 17e18. [12] A. Nagasaki, K. Saitoh, M. Koshiba, Polarization characteristics of photonic crystal fibers selectively filled with metal wires into cladding air holes, J. Opt. Express 19 (2011) 3799e3808. [13] J. Xue, S. Li, Y. Xiao, W. Qin, X. Xin, X. Zhu, Polarization filter characters of the gold-coated and the liquid filled photonic crystal fiber based on surface plasmon resonance, J. Opt. Express 21 (2013) 13733e13740. [14] G.Y. Wang, S.G. Li, G.W. An, X.Y. Wang, Y.Y. Zhao, W. Zhang, Design of a polarized filtering photonic-crystal fiber with gold-coated air holes, J. Appl. Opt. 54 (2015) 8817e8820. [15] C.E. Finlayson, A. Amezcua-Correa, P.J.A. Sazio, N.F. Baril, J.V. Badding, Electricalan d Raman characterization of silicon and germanium-filled microstructured optical fibers, J. Appl. Phys. Lett. 90 (2007) 1583. [16] J. Jung, H. Nam, B.H. Lee, J.O. Byun, N.S. Kim, Fiber Bragg grating temperature sensor with controllable sensitivity, J. Appl. Opt. 38 (1999) 2752e2754. [17] A. Vial, A. Grimault, D. Maclas, D. Barchiesi, M. Chapelle, Improved analytical fit of gold dispersion: application to the modeling of extinction spectra with a finite-difference time-domain methodP, J. Phys. Rev. B 71 (2005) 85416. [18] L.H. Jiang, Y. Zheng, J.J. Yang, L.T. Hou, J.Y. Peng, X.T. Zhao, Design of an ultrashort single-polarization wavelength splitter based on gold-filled squarelattice photonic crystal fiber, J. Opt. Quant. Electron. 48 (2016) 409.
Contents lists available at ScienceDirect
Optical Materials journal homepage: www.elsevier.com/locate/optmat
Design of a novel photonic crystal fiber filter based on gold-coated and elliptical air holes Yunyan Zhao*, Shuguang Li, Qiang Liu, Xinyu Wang Key Laboratory of Metastable Materials Science and Technology, College of Science, Yanshan University, Qinhuangdao, 066004, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 21 May 2017 Received in revised form 17 August 2017 Accepted 18 August 2017
In recent years, photonic crystal fibers have played an important role in the field of optical communications, and the addition of metal materials to photonic crystal fibers have offered new ways to improve the transmission characteristics of optical fibers. We design a new type of gold-coated photonic crystal filter, which utilizes the surface plasmon resonance effect, and study it by using the finite element method. In this paper, we optimise the structure parameters and analyze the numerical results. The numerical results show that the thickness of metal layer and the air holes near the fiber core strongly affect the performance of the polarization filter. For the operating wavelength of 1550 nm, the loss in the y-polarization direction can be as high as 906.9 dB/cm, which is much larger than the x-polarization direction. When the fiber length is longer than 100 mm, the crosstalk in the wavelength range from 1.4 mm to 1.9 mm is greater than 20 dB. The proposed optical fiber can find application as an optical fiber polarization filter. © 2017 Published by Elsevier B.V.
Keywords: Photonic crystal fiber Polarization filter Surface plasmon resonance Gold-coated
1. Introduction As a new communication technology, compared with the traditional optical fiber, photonic crystal fibers (PCFs) [1e3] have many advantages. As time passed, the researchers found that some materials can be applied to optical fiber communication technology, such as liquids [4], liquid crystals [5], oil [6], or metals [7]. The addition of a certain amount of material to the fiber affects its transmission characteristics [8e11]. This attracted the interest of many researchers. More recently, gold-filled and gold-coated photonic crystal fibers have been considered. The results show that the use of metal materials can produce photonic crystal fibers with better transmission performance. After adding the metal material, the surface of the metal will form the surface plasmon polaritons (SPP). In addition, when phase matching conditions between core mode and SPP mode are met, coupling resonance phenomenon will occur at a certain wavelength. Nowadays, many researchers have done a lot of novel designs on this basis. Nagasaki et al. [12] have described that the surface plasmon resonance effect can produce loss peak wavelengths. On the basis of the plasma resonance effect, Xue and Li [13]
* Corresponding author. E-mail address: [email protected] (Y. Zhao). http://dx.doi.org/10.1016/j.optmat.2017.08.029 0925-3467/© 2017 Published by Elsevier B.V.
designed a photonic crystal fiber with selective addition of gold and filled liquid whose loss in the y polarization direction reached 508 dB/cm. Wang proposed a quadrilateral coated metallic photonic crystal fiber which can achieve a resonance strength of 720 dB/cm in the y-polarized direction [14]. The results show that the gold-coated photonic crystal fiber has better filtering effect than the gold-filled photonic crystal fiber. In this paper, we have designed a new type of photonic crystal fiber with elliptical air holes and selectively plated gold to the air holes. Simul-ation results show that, compared with [12e14], the PCF has better polari-zation filter characteristics and higher cross talk (CT)at the communication wavelength. At the same time, we also compared the characteristics of the PCF between gold-coated and gold-filled. 2. Structure and theroretical principle The cross section of the PCF polarized filter with elliptical air holes is shown in Fig. 1. Here, the core is formed by removing an air hole in the center. It has four large air holes and two elliptical air holes around it. At the same time, the whole structure is formed by rotating the quadrilateral by 45 . In order to form the surface plasmon effect, we have coated gold on the upper and lower air holes of the core, respectively. As shown in Fig. 1, d1 and D denote the diameter and lattice spacing of the clad air holes, respectively.
Y. Zhao et al. / Optical Materials 73 (2017) 638e641
639
Fig. 2. PML and scattering boundary conditions.
Fig. 1. Cross section of the proposed photonic crystal fiber filter.
In addition, the diameter of the four large holes is d2, where a and b are the minor axis length and the major axis length of the elliptical hole, respectively. For this structure, the parameters d1, d2, a and b are fixed to 0.8 mm, 0.8 mm, 0.5 mm and 1.0 mm, respectively. The lattice pitch is D ¼ 2 mm and the thickness of the gold layer d is fixed to 20 nm. We use pure silica as the background material. Its chromatic dispersion is calculated by the Sellmeier equation [15]. The refractive index of air is 1. The permittivity of the gold is calculated by the DrudeLorentz model [16]:
εm ¼ ε∞
u2D
uðu jlDÞ
Dε,U2L u2 U2L jGL u
where ε∞ is the high-frequency permittivity, ε∞ ¼ 5.9673; Dε ¼ 1.09, UL and GL are the frequency and the spectral width of the Lorentz oscillator, respectively. u is the angular frequency of guided light, while uD and gD represent the plasma freq-uency and damping frequency. Here, uD/2p ¼ 2113.6 TH Z; gD/2p ¼ 15.92 THZ; UL/2p ¼ 650.07 THZ; GL/2p ¼ 104.86 THZ. As an important parameter of polarizati-on filters, the mode loss of the fiber can be expressed as
L ¼ 8:686
2p
l
Imðneff Þ 104
There are two important parameters in the above equation: l and Im (neff), which represent the wavelength of the incident light and the imaginary part of the effective refractive index of the fiber core [17], and the units correspond to microns and dB/cm, respectively. In the whole process of simulation using the finite element method, we apply the perfectly matched layer (PML) and the scattering boundary conditions (see Fig. 2). When the phase matching condition is reached, the core mode can be strongly coupled with the SPP mode.
3. Numerical results and analysis Fig. 3 shows the fiber core mode and the surface plasmon
polaritons (SPP) mode field distribution. Since we selectively plated the two air holes with gold film, the surface plasmon resonance effect was produced. In this way, the two modes mentioned above will be strongly coupled at a certain wavelength, and there will be greater energy loss in one of the polarization directions of this wavelength, so that it can be used as a polarization filter. When the structural parameters of the fiber are optimized, the peak value of the loss will appear in a certain direction of polarization due to the asymmetry of the structure, so as to achieve a good polarization filtering effect at this wavelength. Fig. 4 shows the loss dispersion profile for the optimized structural configuration. At this time, d1, d2, a and b are fixed at 0.8 mm, 0.8 mm, 0.5 mm and 1.0 mm and the thickness of the gold layer is fixed at 20 nm. It can be clearly seen from the figure that the core mode and the SPP mode of the Y-direction of the 1550 nm wavelength are strongly coupled so that the peak of the loss is much larger than that in the x-direction, and the fiber has a good polarization filtering effect at 1550 nm. Another important parameter of the photonic crystal fiber filter is crosstalk (CT), which can represent the filtering effect of the filter, and it can be defined as [18]
CT ¼ 20lgfexp½ða2 a1ÞLg where a1 and a2 represent the loss in the X and Y directions, whereas L represents the fiber length. Fig. 5 shows the relationship between crosstalk and fiber length. As can be seen from the figure, with the increase in wavelength, CT also showed a certain change trend. When the length of the fiber exceeds 100 mm, in the 1.4e1.9 mm wavelength range, CT are more than 20 dB, which means that the fiber has a good filtering effect and can be used to make the filter. As we know, when the structure of the optical fiber changes, some of its transmission characteristics will change accordingly. Therefore, if we analyze the variation of the influence of parameters on the transmission characteristics, we can have some guiding significance for the manufacture of optical fiber. So we have a simple analysis on some structural parameters, which may have some impact on the transmission characteristics of this fiber. In this paper, we focus on these two parameters: air holes diameter, gold film thickness and the size of the elliptical air hole. Next, we discuss the effect of the four orifices surrounding the core on the fiber filter effect. As shown in Fig. 6, in this paper, when the other parameters remain constant, we make the gradient of d2 from 0.6 mm to 1.1 mm. It can be seen in this band that the loss formant has red shift phenomenon in the y-polarized direction,
640
Y. Zhao et al. / Optical Materials 73 (2017) 638e641
Fig. 3. The electric field distributions of (a)x-polarized (b)y-polarized core mode and (c)x-polarized (d)y-polarized SPP mode.
Fig. 4. The dispersion relation of the optical fiber core mode and SPP mode.
Fig. 6. The variations of the resonance peak for different values of d2.
short axes of the ellipse to analyze its effect on the transmission characteristics. As can be seen from Fig. 7, when we make a series of changes in the size of the ellipse, the loss peak will also change, so as long as we make the appropriate value to the elliptical air hole size, then it will have some certain influence on the optimize structure. In this way, changing the elliptical air hole can be used as
Fig. 5. The peak value variations of the CT for different fiber lengths L ¼ 100 mm (black curve), L ¼ 200 mm (red curve), L ¼ 300 mm (blue curve) and L ¼ 400 mm (green curve). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
which means moving toward the long-wave direction while the loss in the x-polarized direction increases as d2 changes. Again, we take into account the effect of the size of the ellipse. In this section, we try to make a corresponding change in the long and
Fig. 7. The variations of the resonance peak for different values of a and b.
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641
the future for the manufacturing of optical fiber filters. Acknowledgments This work was supported by the National Natural Science Foundation of China (Grant No. 61475134, 61505175) and Key Program of the Natural Science Foundation of Hebei Province (Grant No. F2017203193). References
Fig. 8. The variations of the resonance peak for different thicknesses of the gold film.
an optimization means to change the transmission properties of photonic crystal fibers. Finally, let us see if the thickness of the metal layer to change, the performance of the fiber will be how to change. As in the above case, we use the principle of a single variable, gradually change the thickness of the metal layer, so that it changes from 10 nm to 30 nm. It is clearly seen from Fig. 8 that, along with the change of the metal layer, the y direction of the resonance peak occurs. Obviously, the thickness of the metal layer on the performance of fiber is very significant, so we change the thickness of the metal layer, you can according to the law of change to create what we want. At the same time, we also compared the coated gold film and filled with gold wire. Obviously, compared with the addition of wire, the filtering effect of the coated photonic crystal is better. Therefore, the coated gold film is also a new method to change the performance characteristics of the photonic crystal fiber. 4. Conclusion In this work, we introduce a new type of photonic crystal fiber, and use the finite element method to analyze and compare it. The resonance strength and the impact of the structural parameters of the photonic crystal fiber on the polarization filter characteristics are studied. The numerical results show that the resonance intensity in the y-direction can reach 906.9 dB/cm at the wavelength of 1550 nm. When the fiber length is greater than 100 nm, its crosstalk can be well over 20 dB. Therefore, it can be considered in
[1] P. Russell, Photonic crystal fibers, J. Appl. Phys. Rev. 299 (2003) 358e362. [2] K. Saitoh, M. Koshiba, Photonic bandgap fibers with high birefringence, J. IEEE Phot. Technol. Lett. 4 (2002) 1291e1293. [3] K. Tajima, J. Zhou, K. Nakajima, K. Sato, Ultralow loss and long length photonic crystal fiber, J. Lightw. Technol. 22 (2004) 7e10. [4] T. Matsui, J. Zhou, K. Nakajima, S. Izumi, Dispersion-flattened photonic crystal fiber with large effective area and low confinement loss, J. Lightw. Technol. 23 (2005) 4178e4183. [5] J.H. Liou, S.S. Huang, C.P. Yu, Loss-reduced highly birefringent selectively liquid-filled photonic crystal fibers, J. Opt. Commun. 283 (2010) 971e974. [6] Y. Geng, X. Li, X. Tan, Y. Deng, X. Hong, Compact and ultrasensitive temperature sensor with a fully liquid filled photonic crystal fiber mach-zehnder interferometer, J. IEEE Sens. 14 (2004) 167e170. [7] H.K. Tyagi, M.A. Schmidt, L. Prill Sempere, P. St, J. Russell, Optical properties of photonic crystal fiber with integral micron-sized Ge wire, J. Opt. Express 16 (2008) 17227e17236. [8] D.J. Won, M.O. Ramirez, H. Kang, V. Gopalan, N.F. Baril, J. Calkins, J.V. Badding, P.J.A. Sazio, All-optical modulation of laser light in amorphous silicon-filled microstructured optical fibers, J. Appl. Phys. Lett. 91 (2007) 161112. [9] M. Chen, R. Yu, A. Zhao, Polarization properties of rectangular lattice photonic crystal fibers, J. Opt. Commun. 241 (2004) 365e370. [10] H. Zhao, M. Chen, G. Li, Temperature dependence of the PER in PM-PCF Coil. Chi, J. Opt. Lett. 10 (2012) 17e19. [11] Y. Wang, M. Alharbi, T.D. Bradley, C. Fourcade-Dutin, Hollow-core photonic crystal fibre for high power laser beam delivery, J. High Power Laser Sci. Eng. 1 (2013) 17e18. [12] A. Nagasaki, K. Saitoh, M. Koshiba, Polarization characteristics of photonic crystal fibers selectively filled with metal wires into cladding air holes, J. Opt. Express 19 (2011) 3799e3808. [13] J. Xue, S. Li, Y. Xiao, W. Qin, X. Xin, X. Zhu, Polarization filter characters of the gold-coated and the liquid filled photonic crystal fiber based on surface plasmon resonance, J. Opt. Express 21 (2013) 13733e13740. [14] G.Y. Wang, S.G. Li, G.W. An, X.Y. Wang, Y.Y. Zhao, W. Zhang, Design of a polarized filtering photonic-crystal fiber with gold-coated air holes, J. Appl. Opt. 54 (2015) 8817e8820. [15] C.E. Finlayson, A. Amezcua-Correa, P.J.A. Sazio, N.F. Baril, J.V. Badding, Electricalan d Raman characterization of silicon and germanium-filled microstructured optical fibers, J. Appl. Phys. Lett. 90 (2007) 1583. [16] J. Jung, H. Nam, B.H. Lee, J.O. Byun, N.S. Kim, Fiber Bragg grating temperature sensor with controllable sensitivity, J. Appl. Opt. 38 (1999) 2752e2754. [17] A. Vial, A. Grimault, D. Maclas, D. Barchiesi, M. Chapelle, Improved analytical fit of gold dispersion: application to the modeling of extinction spectra with a finite-difference time-domain methodP, J. Phys. Rev. B 71 (2005) 85416. [18] L.H. Jiang, Y. Zheng, J.J. Yang, L.T. Hou, J.Y. Peng, X.T. Zhao, Design of an ultrashort single-polarization wavelength splitter based on gold-filled squarelattice photonic crystal fiber, J. Opt. Quant. Electron. 48 (2016) 409.