In this work, we explore inverse designed reconfigurable digital metamaterial structures based on phase change material Sb2Se3for efficient and compact integrated nanophotonics. An exemplary design of a 1 × 2 optical switch consisting of a 3 µm x 3 µm pixelated domain is demonstrated. We show that: (i) direct optimization of a domain containing only Si and Sb2Se3pixels does not lead to a high extinction ratio between output ports in the amorphous state, which is owed to the small index contrast between Si and Sb2Se3in such a state. As a result, (ii) topology optimization, e.g., the addition of air pixels, is required to provide an initial asymmetry that aids the amorphous state's response. Furthermore, (iii) the combination of low loss and high refractive index change in Sb2Se3, which is unique among all phase change materials in the telecommunications 1550 nm band, translates into an excellent projected performance; the optimized device structure exhibits a low insertion loss (∼1.5 dB) and high extinction ratio (>18 dB) for both phase states.
We propose and simulate a compact (∼29.5 µm-long) nonvolatile polarization switch based on an asymmetric Sb2Se3-clad silicon photonic waveguide. The polarization state is switched between TM0and TE0mode by modifying the phase of nonvolatile Sb2Se3between amorphous and crystalline. When the Sb2Se3is amorphous, two-mode interference happens in the polarization-rotation section resulting in efficient TE0-TM0conversion. On the other hand, when the material is in the crystalline state, there is little polarization conversion because the interference between the two hybridized modes is significantly suppressed, and both TE0and TM0modes go through the device without any change. The designed polarization switch has a high polarization extinction ratio of > 20 dB and an ultra-low excess loss of < 0.22 dB in the wavelength range of 1520-1585 nm for both TE0and TM0modes.
more » « less- Award ID(s):
- 2003509
- PAR ID:
- 10473676
- Publisher / Repository:
- Optica
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 31
- Issue:
- 6
- ISSN:
- 1094-4087
- Page Range / eLocation ID:
- 10684
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1364/OE.482817
