This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence...This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10% is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.展开更多
Band structures of one-dimensional （1D） photonic crystals （PCs） containing dispersive left-handed metamaterials are studied theoretically. The results show that the structure possesses a type of photonic band gap ...Band structures of one-dimensional （1D） photonic crystals （PCs） containing dispersive left-handed metamaterials are studied theoretically. The results show that the structure possesses a type of photonic band gap originating from total internal reflection （TIR）. In contrast to photonic band gaps corresponding to zero average refractive index and zero phase, the TIR gap exhibits sharp angular effect and has no polarization effect. It should also be noted that band structures of transverse electric （TE） and transverse magnetic （TM） mode waves are exactly the same in the PCs we studied.展开更多
The transmission properties in Fibonacci quasi-periodic photonic crystals containing negative-zero-positive index metamaterials(NZPIM)are investigated systematically.Because of linear dispersion,an asymmetric band gap...The transmission properties in Fibonacci quasi-periodic photonic crystals containing negative-zero-positive index metamaterials(NZPIM)are investigated systematically.Because of linear dispersion,an asymmetric band gap appears near the optical Dirac point(DP)only at an oblique incidence.Zero-n gaps and Bragg gaps exist when the refractive indexes of NZPIM are negative and positive,respectively.We also obtain gaps induced by total reflection on both sides of the DP gap.The corresponding Goos-Hänchen(GH)shifts and phase variations are also demonstrated in detail.It is shown that the characteristics of the band gaps,GH shifts,and phase variations depend crucially on the incident angle,number of periods,and layer thickness.展开更多
In this paper, the photonic band gap （PBG） properties of two dimensional （2D） square lattice photonic crystal structures composed of rectangular cells were studied. The effect of refractive index, rectangles lengt...In this paper, the photonic band gap （PBG） properties of two dimensional （2D） square lattice photonic crystal structures composed of rectangular cells were studied. The effect of refractive index, rectangles length and the ratio of width to length of the rectangles on the PBG properties of the structure with different configura- tions was investigated. It is found that the density of gaps in both modes （transverse electric （TE） and transverse magnetic （TM）） is high for structure composed of rectangular dielectric rods in gaps is very low for structure pores in dielectric material. air, while the density of the composed of rectangular air展开更多
The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectri...The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectric constants (ε', ε") of (TMA)2ZnCl4 crystals were calculated as a function of photon energy. The analysis of the spectra behavior of the absorption coefficient in the absorption region revealed indirect transition. The dispersion of the refractive index is discussed in terms of the sin-gle oscillator Wemple-DiDomenico model. The single oscillator energy (E0), the dispersion energy (Ed), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the ef-fective mass (N/m*) were estimated. The FTIR spectra were recorded to study the functional groups of the as grown and annealed samples.展开更多
A novel polarization channel drop filter （PCDF） based on two-dimensional （2D） photonic crystals （PCs） is presented. It consists of two line defect waveguides and two point defect micro-cavities. In the line-defe...A novel polarization channel drop filter （PCDF） based on two-dimensional （2D） photonic crystals （PCs） is presented. It consists of two line defect waveguides and two point defect micro-cavities. In the line-defect waveguides, the transverse-electric （TE） and transverse-magnetic （TM） polarization lights are guided using photonic band-gap and total internal reflection effect, respectively. The light at the resonant frequency for TE polarization can be transferred from one waveguide to the other using the proposed system. Compared with the existing four-port PCDF based on PCs, the three-port structure can realize a multi-channel wavelength system of PCDF more easily and can be an essential device in future polarization wavelength division multiplexing （PWDM） systems.展开更多
Localized fields in the defect mode of one-dimensional photonic crystals with active impurity are studied with the help of the theory of spontaneous emission from two-level atoms embedded in photonic crystals. Numeric...Localized fields in the defect mode of one-dimensional photonic crystals with active impurity are studied with the help of the theory of spontaneous emission from two-level atoms embedded in photonic crystals. Numerical simulations demonstrate that the enhancement of stimulated radiation, as well as the phenomena of transmissivity larger than unity and the abnormality of group velocity close to the edges of photonic band gap, are related to the negative imaginary part of the complex effective refractive index of doped layers. This means that the complex effective refractive index has a negative imaginary part, and that the impurity state with very high quality factor and great state density will occur in the photonic forbidden band if active impurity is introduced into the defect layer properly. Therefore, the spontaneous emission can be enhanced, the amplitude of stimulated emission will be very large and it occurs most probably close to the edges of photonic band gap with the fundamental reason, the group velocity close to the edges of band gap is verv small or abnormal.展开更多
基金Project supported by the National 973 （Grant No 2004CB719804） and the National Natural Science Foundation of China.
文摘This paper has theoretically studied the characteristic frequencies of band structures in two-dimensional metallic- dielectric photonic crystals. It is demonstrated that a large filling fraction benefits the existence of absolute photonic band gap, while a smaller filling fraction benefits an absolute negative refraction band. In addition, it also finds that the relation between the cut-off frequency of E-polarized wave and the filling fraction exceeding 10% is content with a linear increasing function, whose coefficients are exponential to the normalized lattice constant. These investigations have significant implications for tuning the operational frequencies to desired applications and manufacturing photonic crystals.
基金the Shanghai Rising-Star Program(No.05QMX1459)the National Natural Science Foundation of China(No.60508018)
文摘Band structures of one-dimensional （1D） photonic crystals （PCs） containing dispersive left-handed metamaterials are studied theoretically. The results show that the structure possesses a type of photonic band gap originating from total internal reflection （TIR）. In contrast to photonic band gaps corresponding to zero average refractive index and zero phase, the TIR gap exhibits sharp angular effect and has no polarization effect. It should also be noted that band structures of transverse electric （TE） and transverse magnetic （TM） mode waves are exactly the same in the PCs we studied.
基金supported by the National Natural Science Foundation of China(No.61975109)the Science and Technology Commission of Shanghai Municipal(No.19ZR1417900)。
文摘The transmission properties in Fibonacci quasi-periodic photonic crystals containing negative-zero-positive index metamaterials(NZPIM)are investigated systematically.Because of linear dispersion,an asymmetric band gap appears near the optical Dirac point(DP)only at an oblique incidence.Zero-n gaps and Bragg gaps exist when the refractive indexes of NZPIM are negative and positive,respectively.We also obtain gaps induced by total reflection on both sides of the DP gap.The corresponding Goos-Hänchen(GH)shifts and phase variations are also demonstrated in detail.It is shown that the characteristics of the band gaps,GH shifts,and phase variations depend crucially on the incident angle,number of periods,and layer thickness.
文摘In this paper, the photonic band gap （PBG） properties of two dimensional （2D） square lattice photonic crystal structures composed of rectangular cells were studied. The effect of refractive index, rectangles length and the ratio of width to length of the rectangles on the PBG properties of the structure with different configura- tions was investigated. It is found that the density of gaps in both modes （transverse electric （TE） and transverse magnetic （TM）） is high for structure composed of rectangular dielectric rods in gaps is very low for structure pores in dielectric material. air, while the density of the composed of rectangular air
文摘The transmittance (T) and the reflectance (R) were measured for (TMA)2ZnCl4 single crystals and hence the absorption coefficient (α), extinction coefficient (Kex.), refractive index (n), real and im-aginary dielectric constants (ε', ε") of (TMA)2ZnCl4 crystals were calculated as a function of photon energy. The analysis of the spectra behavior of the absorption coefficient in the absorption region revealed indirect transition. The dispersion of the refractive index is discussed in terms of the sin-gle oscillator Wemple-DiDomenico model. The single oscillator energy (E0), the dispersion energy (Ed), the lattice dielectric constant (εL) and the ratio of free charge carrier concentration to the ef-fective mass (N/m*) were estimated. The FTIR spectra were recorded to study the functional groups of the as grown and annealed samples.
基金supported by the National Natural Science Foundation of China(Nos.60978010,60907032, and 60825103)the Program of Shanghai Subject Chief Scientist(No.09XD1402200)+1 种基金the Natural Science Foundation of Zhejiang Province(No.Y1090169)the Foundation of Zhejiang University of Technology(No. 0901103012408)
文摘A novel polarization channel drop filter （PCDF） based on two-dimensional （2D） photonic crystals （PCs） is presented. It consists of two line defect waveguides and two point defect micro-cavities. In the line-defect waveguides, the transverse-electric （TE） and transverse-magnetic （TM） polarization lights are guided using photonic band-gap and total internal reflection effect, respectively. The light at the resonant frequency for TE polarization can be transferred from one waveguide to the other using the proposed system. Compared with the existing four-port PCDF based on PCs, the three-port structure can realize a multi-channel wavelength system of PCDF more easily and can be an essential device in future polarization wavelength division multiplexing （PWDM） systems.
基金This work was supported by the Natural Science Foun-dation of Jiangsu Province under Grant No.BK2004059.
文摘Localized fields in the defect mode of one-dimensional photonic crystals with active impurity are studied with the help of the theory of spontaneous emission from two-level atoms embedded in photonic crystals. Numerical simulations demonstrate that the enhancement of stimulated radiation, as well as the phenomena of transmissivity larger than unity and the abnormality of group velocity close to the edges of photonic band gap, are related to the negative imaginary part of the complex effective refractive index of doped layers. This means that the complex effective refractive index has a negative imaginary part, and that the impurity state with very high quality factor and great state density will occur in the photonic forbidden band if active impurity is introduced into the defect layer properly. Therefore, the spontaneous emission can be enhanced, the amplitude of stimulated emission will be very large and it occurs most probably close to the edges of photonic band gap with the fundamental reason, the group velocity close to the edges of band gap is verv small or abnormal.
