ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain.
Nat Mater. 2012 Sep;11(9):781-7. doi: 10.1038/nmat3402. Epub 2012 Aug 19.
Numerous optical technologies and quantum optical devices rely on the controlled coupling of a local emitter to its photonic environment, which is governed by the local density of optical states (LDOS). Although precise knowledge of the LDOS is crucial, classical optical techniques fail to measure it in all of its frequency and spatial components. Here, we use a scanning electron beam as a point source to probe the LDOS. Through angular and spectral detection of the electron-induced light emission, we spatially and spectrally resolve the light wave vector and determine the LDOS of Bloch modes in a photonic crystal membrane at an unprecedented deep-subwavelength resolution (30-40 nm) over a large spectral range. We present a first look inside photonic crystal cavities revealing subwavelength details of the resonant modes. Our results provide direct guidelines for the optimum location of emitters to control their emission, and key fundamental insights into light-matter coupling at the nanoscale.
许多光学技术和量子光学器件都依赖于局域发射器与其光子环境的有效耦合，而这一过程由局域光态密度（LDOS）所决定。尽管对 LDOS 的精准掌握至关重要，但传统光学技术无法测量其所有的频率和空间分量。在这里，我们使用扫描电子束作为点光源来探测 LDOS。通过对电子诱导光发射的角度和光谱探测，我们在空前的深亚波长分辨率（30-40nm）下对光子晶体膜中的布洛赫模的光波矢进行了空间和光谱分辨，并确定了 LDOS，该分辨率覆盖了很大的光谱范围。我们首次观察到了光子晶体腔的内部，揭示了共振模式的亚波长细节。我们的研究结果为控制发射器的最佳位置提供了直接的指导，也为纳米尺度下光与物质的耦合提供了关键的基本见解。
