Recent content by krindik

Thanks a lot Born2bwire, u were really helpful.

Hi, Thanks for the response. This is what I understood of its derivation. Hope u could clarify. The electric field due to the dipole can be given by \mathbf{E}(\mathbf{r}) = k^2 \mathbf{G}(\mathbf{r}, \mathbf{r}')\mathbf{p}(\mathbf{r'}) where \mathbf{G}(\mathbf{r}, \mathbf{r}') is the...

Hi all, I know that the electric field generated by a dipole is given by \mathbf{E}= [1-i(\omega/c) r]\frac{3 (\mathbf{p}\cdot\mathbf{r})\mathbf{r}-\mathbf{p} }{r^3}+(\omega/c)^2\frac{\mathbf{p}-(\mathbf{p}\cdot\mathbf{r})\mathbf{r}}{r} e^{i(\omega/c)r} where \mathbf{p} is the dipole's...

Thanks for the reply. Assuming a lossless material with a negative permittivity \epsilon_r < 0 and a permeability will result in a complex number for refractive index n = \sqrt{\epsilon_r \mu_r} thus lossy propagation. An EM wave hitting such a medium will decay within the medium and...

Thanks for the reply. So how can negative permittivity affect wave propagation. We know that a dielectric having a positive permittivity allows EM wave propagation with a reduced velocity than vacuum. Is there a similar explanation for some material that have negative permittivity?

Hi, It is seen that noble metals (gold, silver) show a negative permittivity in optical frequencies. Can somebody explain the physical interpretation of this phenomena? How is the negative permittivity measured? Really appreciate if someone could point me in the correct direction. Thanks.

Thanks :)

Hi, Is there a simplification for the determinant of a symmetric matrix? For example, I need to find the roots of \det [A(x)] where A(x) = \[ \left( \begin{array}{ccc} f(x) & a_{12}(x) & a_{13}(x) \\ a_{12}(x) & f(x) & a_{23}(x) \\ a_{13}(x) & a_{23}(x) & f(x) \end{array}...

Could you give the exact definitions? Or any book? Thanks in advance

Hi, This must be a textbook question but I couldn't find exact definitions(quantitative) of these measurements Extinction spectra: Absorption spectra: Transmission spectra: eg. Lets say electric field spectrum of some location/surface is calculated by illuminating a source with and without the...

Thanks for the words of wisdom ! I was a bit confused in going from chapter 2 in this excellent book as nowhere did I read about the discrete nature of k: \frac{2 \pi}{N a} in an non-infinite crystal. I can understand the periodic nature of k in: \mathbf{H}(r) = e^{i k \cdot r}...

Hi, I have this quite basic question regarding photonic crystals. As I understand, a periodic dielectric structure (photonic crystal) has modes (spatial profiles) at discrete frequencies from: \nabla \times \Big( \frac{1}{\epsilon(r)}\nabla \times H(r) \Big) = \frac{\omega^2}{c^2} H(r)...

Thanks a lot. Before reading the book i'll just make some points to clarify what you meant. - If E and H fields are known in a given area (or volume), the equivalent electric and magnetic currents can be calculated on the boundary (or surface). - These can be excited to get the E, H...

Hi, Lets say the electric and magnetic fields in an closed surface (2-D) are known. Is it possible to derive electric/magnetic currents that can create these fields? We can assume that the closed surface is homogenous with constant permittivity and permeability. Is this a well known...

Thanks. Can u point me to some text or online notes where it uses the averaging method?