Absorbing infrared radiation efficiently is important for critical applications such as thermal imaging and infrared spectroscopy. Common infrared absorbing materials are not standard in Si VLSI technology. We demonstrate ultra-broadband mid-infrared absorbers based purely on silicon. Broadband absorption is achieved by the combined effects of free carrier absorption, and vibrational and plasmonic absorption resonances. The absorbers, consisting of periodically arranged silicon gratings, can be fabricated using standard optical lithography and deep reactive ion etching techniques, allowing for cost-effective and wafer-scale fabrication of micro-structures. Absorption wavebands in excess of 15 micrometers (5–20 μm) are demonstrated with more than 90% average absorptivity. The structures also exhibit broadband absorption performance even at large angles of incidence (θ = 50°), and independent of polarization.

View the article online for updates and enhancements. Recent citations Wideband 'black silicon' for mid-infrared applications K Gorgulu et al

We propose an all-ZnO bilayer microbolometer, operating in the long-wave infrared regime that can be implemented by consecutive atomic layer deposition growth steps. Bilayer design of the bolometer provides very high absorption coefficients compared to the same thickness of a single ZnO layer. High absorptivity of the bilayer structure enables higher performance (lower noise equivalent temperature difference and time constant values) compared to single-layer structure. We observe these results computationally by conducting both optical and thermal simulations.

We demonstrate a highly scalable silicon photonic neural network architecture enabling arbitrarily complex, on-chip optical functionality. We use this architecture to demonstrate wideband power splitters, achieving near-lossless and flat-top transmission bands.

In this paper, we investigate the absorption of mid-infrared light by low resistivity silicon textured via deep reactive ion etching. An analytical description of the wave propagation in black silicon texture is presented, showing agreement with the experiment and the computational analysis. We also study the dependence of absorption spectrum of black silicon structure on the electrical conductivity of silicon substrate. The structures investigated unveil wideband, allsilicon infrared absorbers applicable for infrared imaging and spectroscopy with simple CMOS compatible fabrication suitable for optoelectronic integration.