It was recently pointed out to us that the refractive index profiles given in Fig. 2 were incorrect [2]; they correspond to a different spectral target. The proper refractive index profiles of the “house-like” filter are given here. The total optical thickness is increased to 32µm. This was necessary to get a flat reflectance across the long-wavelength tower. However, the design substitutions do not affect the main conclusions of the paper.

We also would like to clarify the SWIFT-phase operation and the iterative process for the design of the “house-like” filter. A portion of the long-wavelength tower was not included in the SWIFT-phase calculation. This improved the refractive index distribution and the spectral fit in Fig. 2 (b), and potentially made the final refractive index profile more predictable since the required corrections were smaller. Moreover, the refractive index sampling interval was relatively crude (91.84 nm in optical thickness) in Fig. 2 (b). During the subsequent iterations, the refractive index sampling interval was reduced to improve spectral fit.

More information about the refractive index profiles can be obtained by contacting the authors.

 

Fig. 2. Refractive-index profiles and reflectance spectra for a house-like reflector calculated with (a) a zero phase, (b) a SWIFT-phase without using some portion of the long-wavelength tower in phase calculation, (c) a SWIFT-phase combined with iterations. The red dashed line is the design target and the black lines are the synthesized spectra.

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