Shenghong Liu

Field representations in general rotationally uniaxial anisotropic media using spherical vector wave functions

Figure 4 Optical power at the two lasing wavelengths, as measured by photodiodes 1 and 2 in the experimental setup. The changing between the two states every 10 ms can be seen clearly The optical powers at wavelengths l and l were observed 12 . on an oscilloscope via photodiodes PD 1 and PD 2 . The oscilloscope traces are shown in Figure 4. The switching between states every 10 ms can be seen clearly. Furthermore, the flip-flop state is stable in the time between the state changes. 4. CONCLUSION An optical flip-flop was presented based on two simple lasers diodes which act as a master]slave pair. The two lasers are coupled so that only light at the lasing wavelength of one laser is injected into the other laser. The flip-flop state at any given time is determined by which laser is the master and which is the slave. A rate equation model was used to model the flip-flop. Steady-state characteristics of the flip-flop were obtained from the rate equation model. Flip-flop operation is not dependent on second-order laser effects such as resonant frequency shifts or gain saturation. Hence, the flip-flop should be able to be implemented in a wide variety of technologies, particularly integrated optics using semiconductor gain regions and gratings for wavelength-dependent mirrors. The flip-flop was experimentally demonstrated using laser diodes with antireflection coatings. ACKNOWLEDGMENT

Circular cylindrical waveguide filled with uniaxial anisotropic media electromagnetic fields and dyadic Green's functions

Electromagnetic fields in a circular cylindrical conducting waveguide filled with uniaxial anisotropic media are formulated in this paper by using Fourier transformations. These fields are obtained as a superposition of the TE (or ordinary) and TM (or extraordinary) modes satisfying, respectively, different characteristic equations. Lastly, the dyadic Greens function is derived using the Ohm-Rayleigh method and represented by vector wave functions expansion.

On the constitutive relations of chiral media and Green's dyadics for an unbounded chiral medium

Different constituti e relations and the limitation of some forms in the presence of exciting sources are discussed. Born’s constituti e relations show a wider applicability in both source-free and sourceincorporated cases. A new mapping method is introduced to obtain the spatial representation of the Green’s dyadics from the spectral one. This method is first erified in the case where Post’s relations are used, and then applied to rigorously deri e the Green’s dyadics in an unbounded chiral medium characterized by Born’s constituti e relations. The final expressions are different from and should be more strict than the pre ious results obtained by simply applying the mapping relations. Q 1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 357]361, 1999.

Scattering by an Arbitrarily Shaped Rotationally Uniaxial Anisotropic Object: Electromagnetic Fields and Dyadic Green's Fucntions

A system for stacking continuous folded forms or web coming from a folder and separator and moving to a conveyor. A table is positioned adjacent and in line with the conveyor and in a position for receiving a horizontally-extending stack of folded forms disposed on the table top. The table is a tiltable table and is able to be tilted from a substantially-horizontal position to a substantially-vertical position to likewise move the stack from a horizontal to a vertical stack position. A cart is movable to a position adjacent to the tilted table for receiving from the table the vertical stack for support on the cart. The cart can include a plurality of storage locations that can each be provided with a stack.

Rectangular Conducting Waveguide Filled With Uniaxial Anisotropic Media: a Modal Analysis and Dyadic Green's Function - Abstract

Electromagnetic fields in a rectangular conducting waveguide filled with uniaxial anisotropic media are analyzed in this paper using Fourier transform. TE modes and TM modes are found to be related to the ordinary waves and extraordinary waves, respectively. The calculated dispersion curves are depicted and the effects of the material parameters on the cutoff frequencies are shown. The cutoff frequencies change considerably especially for TM modes. The field distributions are plotted to compare with the isotropic rectangular waveguide. The electric type dyadic Greens function due to electric source is derived in the form of vector wave functions expansion by applying Ohm-Rayleigh method. The final result shows that the parameters of the medium have close and intricate relationships with the properties of the Greens function, hence, influencing the propagation of the guided wave. The dyadic Greens function is reducible to that in the isotropic medium. From Maxwell equations, the magnetic dyadic Greens function due to electric source is also given. As the application of the dyadic Greens functions, numerical results of the fields inside the waveguide excited by an infinitesimal dipole are present.

Theory of Gyroelectric Waveguides - Abstract

Circular conducting waveguides filled with gyroelectric media are studied in this paper and the dyadic Greens functions in these waveguides are obtained for the first time. The electric and magnetic fields in the waveguide are expressed in terms of cylindrical vector wave function expansion. It is shown that each of the eigenmodes in the waveguide consists of two eigenwaves whose wave numbers can be determined by the characteristic equation. Dispersion relation is obtained by applying boundary conditions to the eigenmodes. Mode orthogonality is discussed before the orthogonal relations are formulated and then used to determine the expansion coefficients of electric and magnetic fields. The complete expansions of both the electric and the magnetic dyadic Greens functions are finally obtained. The calculated dispersion curves are depicted and discussed while effects of gyrotropy are shown.

Circular Chiroferrite Waveguides: Dispersion Curves and Dyadic Green's Functions

In this paper, the eigenmodes in circular chiroferrite waveguides are studied and the dyadic Greens functions are derived for the first time. The electric and magnetic fields are expanded by cylindrical vector wave eigenfunctions. It is shown that each of the eigenmodes consists of two eigenwaves corresponding to two different polarizations. A dispersion relation is obtained by imposing boundary conditions on the eigenmodes, and the dispersion curves are depicted for various medium parameters. The effects of the uniaxial anisotropy, the gyrotropy, and the chirality are discussed individually. The mode orthogonality is built by introducing complementary testing modes. Hence, the expansion coefficients of the electric and magnetic fields are determined and the dyadic Greens functions are formulated. In order to obtain the complete expansions of the dyadic Greens functions, the singularities of chiroferrite waveguides are also discussed.In this paper, the eigenmodes in circular chiroferrite waveguides are studied and the dyadic Greens functions are derived for the first time. The electric and magnetic fields are expanded by cylindrical vector wave eigenfunctions. It is shown that each of the eigenmodes consists of two eigenwaves corresponding to two different polarizations. A dispersion relation is obtained by imposing boundary conditions on the eigenmodes, and the dispersion curves are depicted for various medium parameters. The effects of the uniaxial anisotropy, the gyrotropy, and the chirality are discussed individually. The mode orthogonality is built by introducing complementary testing modes. Hence, the expansion coefficients of the electric and magnetic fields are determined and the dyadic Greens functions are formulated. In order to obtain the complete expansions of the dyadic Greens functions, the singularities of chiroferrite waveguides are also discussed.

Reply to “Comments on ‘On the Constitutive Relations of Chiral Media and Green's Dyadics for an Unbounded Chiral Medium’”

It is again emphasized that the sources must be trans( formed accordingly in order to make DBF relations and Post’s or ) Tellegen’s relations totally equi¤alent. For gi¤en sources, different results can be obtained by making different choices of the relations. Q 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 278, 2000.

Scattering By an Arbitrarily Shaped Rotationally Uniaxial Anisotropic Object: Electromagnetic Fields and Dyadic Green's Fucntions - Abstract *

The electromagnetic scattering by a three-dimensional arbitrarily shaped rotationally uniaxial anisotropic object is studied. Electromagnetic fields in a uniaxial medium are solved for first using the method of separation of variables, and then expressed in a very compact form by introducing the modified spherical vector wave functions. The equivalence theorem and the T-matrix method are applied in the analysis of the scattering problem. The scattered fields and the dyadic Greens functions both external and internal to the scatterer are derived in terms of spherical vector wave functions and matrix-form coefficients. Through making use of the dyadic Greens functions obtained, numerical results are provided for an incident field excited by an infinitesimal dipole. The scatterers are assumed to be prolate and oblate dielectric spheroids with the rotational z-axis. The angular scattering intensities in far-zone are plotted for all these cases. And some conclusions are also drawn eventually from numerical discussions.

Arbitrary cross-sectional cylindrical conducting waveguide filled with uniaxial anisotropic media: EM fields and dyadic Green's functions

Electromagnetic fields in arbitrary cross-sectional cylindrical conducting wave-guides filled with uniaxial anisotropic media are analyzed using Fourier transform. The wavefields are decomposed into ordinary wave and extraordinary wave which take TE modes and TM modes, respectively. As the applications, the dyadic Greens functions, in terms of vector wave functions, are derived for circular, rectangular, and parallel-plate waveguides separately.