Fig. 3. Measurement results at the angles of incidence θ = −60^∘,0^∘,and 60^∘.

(A) Polarization space representation of the device functionality. At each angle, the device induces a rotation (blue arrows) on the Poincaré sphere, which converts the input polarization (∣H⟩, blue dots) to the output polarization states (∣out⟩, green dots). The rotation axis (red arrows) is determined by the device’s eigen-polarization states ($\mid {\mathrm{\lambda }}_{\text{eig}}^{\pm }⟩$, red dots). (B) Measured (black) and simulated (brown) eigen-polarization states ($\mid {\mathrm{\lambda }}_{\text{eig}}^{\pm }⟩$). One can see that at ±60^∘, the device is elliptically birefringent [corresponding to the out-of-equatorial-plane rotation axis in (A)], whereas at normal incidence, the device is linearly birefringent. At each angle, the two eigen-polarization states, $\mid {\mathrm{\lambda }}_{\text{eig}}^{+}⟩$ and $\mid {\mathrm{\lambda }}_{\text{eig}}^{-}⟩,$are approximately orthogonal to each other. Note that the eigen-polarization states at ±60^∘ have opposite handedness. (C) Measured (black) and simulated (brown) output polarization states (∣out⟩) for a fixed incident polarization ∣H⟩. By design, the output polarization becomes right circular polarization, horizontal linear polarization, and 45° linear polarization at θ = −60^∘,0^∘, and 60^∘ respectively. The measured DOCP (14) is 0.94 at −60^∘. The measured DOLP (14) is 0.99 and 0.96 at θ = 0^∘,60^∘ respectively.