## Abstract

We report on a light-dispersing device consisting of two transmission gratings and a waveplate. The gratings separate two orthogonal polarization components of light incident at the Bragg angle. The waveplate, which is sandwiched between the gratings, functions as a polarization converter for oblique light incidence. With these optical parts suitably integrated, the resulting device efficiently diffracts unpolarized light with high spectral resolution. Using coupled-wave theories and Mueller matrix analysis, we constructed a device for a wavelength range of $680\pm 50\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{nm}$ with a 400 nm grating period. From the characterization of this optical device, we validated the proposed polarization-independent, light-dispersing concept.

© 2014 Optical Society of America

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### Equations (6)

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(1)
$$\eta =\alpha (1-{\beta}^{\prime}){C}_{1}\text{\hspace{0.17em}}\mathrm{cos}{(\delta )}^{2}+{\alpha}^{\prime}(1-\beta ){C}_{0}\text{\hspace{0.17em}}\mathrm{sin}{(\delta )}^{2},$$
(2)
$$f=[\lambda /2p-{(1.0-{n}_{\text{eff}}^{2})}^{1/2}]/[{({n}^{2}-{n}_{\text{eff}}^{2})}^{1/2}-{(1.0-{n}_{\text{eff}}^{2})}^{1/2}],$$
(3)
$$\varphi =\mathrm{arctan}[\mathrm{cos}({\theta}^{\prime})\mathrm{tan}\text{\hspace{0.17em}}45\xb0],$$
(4)
$$\eta =\alpha (1-{\beta}^{\prime})\mathrm{sin}{(2\varphi )}^{2}\text{\hspace{0.17em}}\mathrm{cos}{(\delta )}^{2}+{a}^{\prime}(1-\beta )\mathrm{sin}{(\mathrm{\Delta}/2)}^{2}\text{\hspace{0.17em}}\mathrm{sin}{(\delta )}^{2},$$
(5)
$$D=F\text{\hspace{0.17em}}\mathrm{sin}(y)=F{[1-{(u{u}^{\prime}+v{v}^{\prime}+w{w}^{\prime})}^{2}]}^{1/2},$$
(6)
$${M}_{11}=[1-(1-\mathrm{cos}({R}_{2}))\mathrm{sin}{(2\varphi )}^{2}]\times [1-(1-\mathrm{cos}({R}_{1}))\mathrm{sin}{(2\varphi )}^{2}]\phantom{\rule{0ex}{0ex}}-(1-\mathrm{cos}({R}_{2}))\times (1-\mathrm{cos}({R}_{1}))\mathrm{sin}{(2\varphi )}^{2}\text{\hspace{0.17em}}\mathrm{cos}{(2\varphi )}^{2}+\mathrm{sin}({R}_{2})\mathrm{sin}({R}_{1})\mathrm{sin}{(2\varphi )}^{2}.$$