Thermo-optic VO2-based silicon waveguide mid-infrared router with asymmetric activation thresholds and large bi-stability.

We report a novel four-port optical router that exploits non-linear properties of vanadium dioxide (VO2) phase-change material to achieve asymmetrical power threshold response with power limiting capability. The scope of this study lies within the concept, modeling, and simulation of the device, with practical considerations in mind for future experimental devices. The waveguide structure, designed to operate at the wavelength of 5.0 µm, is composed of a silicon core with air and silicon dioxide forming the cladding layers. Two ring resonators are employed to couple two straight waveguides, thus four individual ports. One of the ring resonators has a 100-nm-thick VO2 layer responsible for non-linear behavior of the device. The router achieves 56.5 and 64.5 dB of power limiting at the forward and reverse operating modes, respectively. Total transmission in the inactivated mode is 75%. Bi-stability and latching behavior are demonstrated and discussed.

Thermo-optic VO2-based silicon waveguide mid-infrared router with asymmetric activation thresholds and large bi-stability: errata.

The authors report an error in the phrasing and citation of the reference to simulation model input data in [Opt. Express31(14), 23260202310.1364/OE.493895]. The original phrasing misplaced "heat capacity" after the in-text citation, where the intended phrase was "electrical conductivity," and heat capacity was intended to be cited with thermal conductivity as external measured data. In the reference itself, the source cited for thermal conductivity and heat capacity was errantly cited as H. Kizuka, et al., Jpn. J. Appl. Phys.54, 053201 (2015)10.7567/JJAP.54.053201. The JJAP paper shows data for both thermal properties of VO2; however, the data utilized for our model input parameters are found in [J. Miranda, et al., Phys. Rev. B 98, 075144 (2018)], including heat capacity data reproduced therein from [T. Kawakubo and T. Nakagawa, J. Phys. Soc. Jap. 19, 4 (1964)]. There are no effects on the simulated data nor conclusions of this article due to the error.

Microconical silicon mid-IR concentrators: spectral, angular and polarization response.

It is widely discussed in the literature that a problem of reduction of thermal noise of mid-wave and long-wave infrared (MWIR and LWIR) cameras and focal plane arrays (FPAs) can be solved by using light-concentrating structures. The idea is to reduce the area and, consequently, the thermal noise of photodetectors, while still providing a good collection of photons on photodetector mesas that can help to increase the operating temperature of FPAs. It is shown that this approach can be realized using microconical Si light concentrators with (111) oriented sidewalls, which can be mass-produced by anisotropic wet etching of Si (100) wafers. The design is performed by numerical modeling in a mesoscale regime when the microcones are sufficiently large (several MWIR wavelengths) to resonantly trap photons, but still too small to apply geometrical optics or other simplified approaches. Three methods of integration Si microcone arrays with the focal plane arrays are proposed and studied: (i) inverted microcones fabricated in a Si slab, which can be heterogeneously integrated with the front illuminated FPA photodetectors made from high quantum efficiency materials to provide resonant power enhancement factors (PEF) up to 10 with angle-of-view (AOV) up to 10°; (ii) inverted microcones, which can be monolithically integrated with metal-Si Schottky barrier photodetectors to provide resonant PEFs up to 25 and AOVs up to 30° for both polarizations of incident plane waves; and iii) regular microcones, which can be monolithically integrated with near-surface photodetectors to provide a non-resonant power concentration on compact photodetectors with large AOVs. It is demonstrated that inverted microcones allow the realization of multispectral imaging with ∼100 nm bands and large AOVs for both polarizations. In contrast, the regular microcones operate similar to single-pass optical components (such as dielectric microspheres), producing sharply focused photonic nanojets.