Solution-processed cavity and slow-light quantum electrodynamics in near-infrared silicon photonic crystals
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(a) Schematic of measurement schemes used in this work. (i) Cavity radiation, where a tunable laser source (a) is coupled through the waveguide and the cavity radiation collected from the top of the device. (ii) Waveguide transmission where a supercontinuum laser source (b) is used. (iii) Cross polarization, where the tunable laser source (d) is coupled to the cavity mode vertically, and the radiation are also collected in the same direction (reflection). (iv) QD PL either at the cavity or waveguide regions, where a 980 nm diode laser (c) is used to excite the QD vertically and the QD radiation is collected from the top (e). (b) SEM image of a typical PhC shown with single QDs (6 nm diameter) on the surface. Scale bar: 100 nm. (c) QD characterization of cavity modes for different filling factors (, ), along with a cross-polarization measurement (gray, high resolution). Device are around 250. (Inset) Cross-polarization spectroscopy of device without dots shows two closely spaced modes .
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Coupled QD-cavity measurements for a PhC cavity mode in a PhCWG device. (a) Cross-polarization spectroscopy (blue) showing a non-Lorentzian lineshape at the cavity resonance. (b) Waveguide characterization (green, lower-most spectrum, at room temperature) and QD PL showing signatures of the cavity mode at room and cryogenic temperatures. (c) SEM of dots at the cavity showing very few dots on the device surface and few QDs along the hole sidewalls and at the bottom interface. (d) One of the PhC holes is shown in detail where three single QD can be clearly seen from the SEM. Scale bars: in (c) and 100 nm in (d).
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(a) Projected band structure for a SOI PhCWG with hole radius of , with the dielectric (green) and air (blue) bands shown. The blue thick slanted line represents the light line. The fundamental and second order TE propagating modes are shown in black and red, respectively, and both modes exhibit near-flat dispersion at the mode onsets, allowing for enhanced light-matter interactions. (b) TE transmission for a device with the parameters used in (a) and containing QDs on the surface showing good agreement with the projected band structure. The cavity mode is shown in red. (c) Projected band structures for design radii of (solid) and (dashed) showing the shifts in the band structure features. (d) Waveguide enhancements for QD emission coupled to the second-order (odd) PhCWG modes for both design radii, showing a shift of 60 nm between the two cases.
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