We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the inp...We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the input wavelength is changed from 1290 nm to 1310 rim, which signifies an angular dispersion of 0.5°/am （＂Superprism＂ phenomenon）. Such a strong angular dispersion is of the order required for WDM systems. By tuning the incident angle, light beams with up to 20° divergence were collimated over a 25 nm （1285 nm to 1310 nm） bandwidth using a triangular lattice （＂Supercollimator＂ phenomenon）. The wavelength collimating range can be extended from 25 nm to 40 nm by changing the lattice from triangular to square. These two devices can be realized in the same configuration, simply by tuning the wavelength. Sources of loss are discussed.展开更多
We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectro...We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.展开更多
The diffraction and refraction of light beam in optical periodic structures can be determined by the photonic band-gap structures of spatial frequency.In this paper,by employing the equation governing the nonlinear li...The diffraction and refraction of light beam in optical periodic structures can be determined by the photonic band-gap structures of spatial frequency.In this paper,by employing the equation governing the nonlinear light propagations in photorefractive crystals,we study the photonic band-gap structures, Bloch modes,and light transmission properties of optically induced planar waveguide arrays.The relationship between the photonic band-gap structures and the light diffraction characteristics is discussed in detail.Then the influence of the parameters of planar waveguide arrays on the band-gaps structures,Bloch modes,and linear light transmissions is analyzed.It is revealed that the linear light transmission properties of waveguide arrays are tightly related to the diffraction relationships determined by band-gap structures.And the Bloch modes corresponding to different transmission bands can be excited by different excitation schemes.Both the increases of the intensity and the period of the array writing beam will lead to the broadening of the forbidden gaps and the concentration of the energy of the Bloch modes to the high-index regions.Furthermore,the broadening of the forbidden gaps will lead to separation and transition between the Bloch modes of neighboring bands around the Bragg angle.Additionally,with the increase of the intensity of the array writing beams,the influences from light intensity will tend to be steady due to the saturation of the photorefractive effect.展开更多
文摘We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the input wavelength is changed from 1290 nm to 1310 rim, which signifies an angular dispersion of 0.5°/am （＂Superprism＂ phenomenon）. Such a strong angular dispersion is of the order required for WDM systems. By tuning the incident angle, light beams with up to 20° divergence were collimated over a 25 nm （1285 nm to 1310 nm） bandwidth using a triangular lattice （＂Supercollimator＂ phenomenon）. The wavelength collimating range can be extended from 25 nm to 40 nm by changing the lattice from triangular to square. These two devices can be realized in the same configuration, simply by tuning the wavelength. Sources of loss are discussed.
文摘We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.
基金Supported by the Youth for Northwestern Polytechnical University(NPU)Teachers Scientific and Technological Innovation Foundationthe NPU Foundation for Fundamental Research,and the Doctorate Foundation of NPU(Grant No.CX200514)
文摘The diffraction and refraction of light beam in optical periodic structures can be determined by the photonic band-gap structures of spatial frequency.In this paper,by employing the equation governing the nonlinear light propagations in photorefractive crystals,we study the photonic band-gap structures, Bloch modes,and light transmission properties of optically induced planar waveguide arrays.The relationship between the photonic band-gap structures and the light diffraction characteristics is discussed in detail.Then the influence of the parameters of planar waveguide arrays on the band-gaps structures,Bloch modes,and linear light transmissions is analyzed.It is revealed that the linear light transmission properties of waveguide arrays are tightly related to the diffraction relationships determined by band-gap structures.And the Bloch modes corresponding to different transmission bands can be excited by different excitation schemes.Both the increases of the intensity and the period of the array writing beam will lead to the broadening of the forbidden gaps and the concentration of the energy of the Bloch modes to the high-index regions.Furthermore,the broadening of the forbidden gaps will lead to separation and transition between the Bloch modes of neighboring bands around the Bragg angle.Additionally,with the increase of the intensity of the array writing beams,the influences from light intensity will tend to be steady due to the saturation of the photorefractive effect.
