The resonant modes of two-dimensional planar photonic crystal microcavities patterned in a free-standing InP slab are probed in a novel fashion using a long working distance microscope objective to obtain cross-polarized resonant scattering and second-harmonic spectra. We show that these techniques can be used to do rapid effective assays of large arrays of microcavities that do not necessarily contain resonant light-emitting layers. The techniques are demonstrated using microcavities comprised of single missing-hole defects in hexagonal photonic crystal hosts formed with elliptically shaped holes. These cavities typically support two orthogonally polarized resonant modes, and the resonant scattering and harmonic spectra are well fitted using a coherent sum of Lorentzian functions. The well-defined coherence between the two resonant features is explained in terms of a microscopic harmonic oscillator model. The relative merits of these techniques are quantitatively compared with the more commonly used cavity-enhanced photoluminescence technique.
An intersubband Raman laser has been realized in an artificial GaAs/AlGaAs three-level quantum-well structure. A CO2 laser in resonance with the one-to-three level transition is used as the pump, while the lasing emission occurs via the three-to-two level transition. The one-to-two level spacing is designed to be in resonance with the AlAs-like longitudinal optical phonon mode, favoring the Raman process. This work presents an alternative mechanism for realizing intersubband lasers and opens up new possibilities in reaching the far infrared region and achieving room-temperature operation.
This tutorial explores ethical implications of cognitive load theory and intersectional theory on technical and professional communication and proposes plain language as an ethical imperative to redress social inequities. Key concepts: When the cognitive load of a learning task is too high and overwhelms working memory, learning is impaired. The greater stress and mental burden that marginalized populations experience can leave less working memory available for reading and learning. Using plain language to reduce cognitive load can be considered a political act that increases marginalized populations' opportunities to understand. Key lessons: 1. Consider whether marginalized populations are part of your audience. 2. Using personas to represent those populations, audit their mental burden to exercise cognitive empathy. 3. Consider reducing cognitive load via plain language an ethical imperative. Implications for practice: Assessing the presence and absence of specific marginalized groups is iterative and takes practice, but developing plain-language communications that
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