## Abstract

A Wollaston prism-like binary dielectric grating is presented and analyzed. It behaves like a transmission grating, differentially and symmetrically blazed for the two crossed polarization states, TE and TM. The phase profile is obtained by means of subwavelength structures etched in a high optical index isotropic dielectric medium (gallium arsenide, for instance). The performance of the device is illustrated by numerical examples and sketched in terms of spectral bandwidth and of extinction ratio. Some practical issues related to the fabrication are discussed.

© 2005 Optical Society of America

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### Equations (8)

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(1)
$${n}_{TE}=\sqrt{f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}}\sqrt{1+\frac{1}{f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}}{\left(\frac{\Lambda}{\lambda}\right)}^{2}\sum _{r\ne 0}\frac{{\epsilon}^{-r}{\epsilon}^{r}}{{r}^{2}}}$$
(2)
$${n}_{TM}=\sqrt{\frac{{\epsilon}_{1}{\epsilon}_{2}}{f{\epsilon}_{2}+\left(1-f\right){\epsilon}_{1}}}\sqrt{1+{\left(\frac{{\epsilon}_{1}{\epsilon}_{2}}{f{\epsilon}_{2}+\left(1-f\right){\epsilon}_{1}}\right)}^{2}{\left(\frac{\Lambda}{\lambda}\right)}^{2}\sum _{r\ne 0}\sum _{m\ne 0}\frac{{a}^{-r}{a}^{m}{\epsilon}^{r-m}}{mr}}$$
(3)
$$\epsilon \left(x\right)=\sum _{q}{\epsilon}^{q}{e}^{i\frac{2\pi}{\Lambda}qx}$$
(4)
$${n}_{TE}=\sqrt{f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}}\sqrt{1+\frac{{\pi}^{2}}{3}{\left(f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}\right){\left(\frac{f\left(1-f\right)\Lambda}{\lambda}\right)}^{2}\left(\frac{{\epsilon}_{1}-{\epsilon}_{2}}{f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}}\right)}^{2}}$$
(5)
$${n}_{TM}=\sqrt{\frac{{\epsilon}_{1}{\epsilon}_{2}}{f{\epsilon}_{2}+\left(1-f\right){\epsilon}_{1}}}\sqrt{1+\frac{{\pi}^{2}}{3}{\left(f{\epsilon}_{1}+\left(1-f\right){\epsilon}_{2}\right){\left(\frac{f\left(1-f\right)\Lambda}{\lambda}\right)}^{2}\left(\frac{{\epsilon}_{1}-{\epsilon}_{2}}{f{\epsilon}_{2}+\left(1-f\right){\epsilon}_{1}}\right)}^{2}}$$
(6)
$${n}_{\mathit{GaAs}}\left(En\right)=\sqrt{7.1+\frac{3.78}{1-0.180{\mathit{En}}^{2}}-\frac{1.97}{{\left(30.08\mathit{En}\right)}^{2}-1}}$$
(7)
$${t}_{\theta}\left(x\right)=\sum _{v}{c}_{v,\theta}\mathrm{exp}\left(iv\frac{2\pi}{\Lambda}x\right)$$
(8)
$${ER}_{TE}={\mid \frac{{c}_{-v,TM}}{{c}_{v,TE}}\mid}^{2}$$