Optimized aperiodic highly directional narrowband infrared emitters

Optimized aperiodic broadband visible absorbers

“…2) in an effort to maximize the power emitted by the structure in the visible while maximizing its efficiency. We use a hybrid optimization method consisting of a micro-genetic global optimization algorithm [11][12][13][14][15][16][17], coupled to a local optimization algorithm [18,19], to determine the best dimensions for four-layer structures. The genetic algorithm is an iterative optimization procedure which starts with a randomly selected population of potential solutions and evolves toward improved solutions; once the population converges, the local optimization algorithm finds the local optimum.…”

Efficient Vertical-Cavity Mid-IR Thermal Radiation to Silicon-Slab Waveguide Coupling Using a Shallow Blazed Grating

“…Detailed descriptions of the 1D-VERTE domains simulated by Transfer-Matrix Methods can be found elsewhere [1][2][3]. In contrast to previous works, the reflection region, i.e., the region the light is coupled into (see Figure 1a), was chosen to be silicon instead of air, which does not change the resonant (vacuum-) wavelength.…”

“…Perfect electric conducting boundaries at the remaining side walls ensure that there are no further absorbing losses in the simulated domain. By Kirchhoff's law (see e.g., [3]), the fraction absorbed by the metal AMetal(θ,λ) at a specific wavelength λ and angle θ is equal to the emittance ϵ Metal (θ,λ) of the stack configuration with respect to radiation into the WG at thermal equilibrium. Thus, in terms of reciprocity AMetal(θ,λ) = ϵ Metal (θ,λ) corresponds to the energy fraction coupled into the waveguide from a cavity mode created by thermal radiation when it is used as an emitter.…”

“…As the VERTE concept can also feature very individual stack configurations with varying layer numbers and layer thicknesses, also different dispersion behavior can be achieved [3]. The dispersion behavior of the grating can be estimated from the grating Equation (4) 2πn…”

Optimized aperiodic multilayer structures for use as narrow-angular absorbers

“…We previously showed that optimized aperiodic multilayer structures can lead to narrowband, highly directional thermal infrared emitters. 36 In this work, structures are designed to operate in the visible. We note that the properties of the materials used are very different in these two wavelength ranges.…”