510
19 Dielectric Structures
(a)
(b)
(c)
(d)
(e)
Fig. 19.30 Simulated near-field intensity pattern of modes in a cavity with hexagonal cross section (absolute value of
electric field in linear grey scale): Modes (N = 4) with (a) symmetry −a and (b) mode 4+ (nomenclature from [1659])
for n = 2.1 and k R = 3.1553 − i0.0748. Modes (c) 26− and (d) 26+ for n = 1.466 and k R = 22.8725 − i0.1064. The
displayed modes have a chiral pattern. Emission originates mostly from the corners. e Micro-photoluminescence spectra
of a single ZnO nanopillar. The three topmost curves are unpolarized. The curve labeled ‘bulk’ shows the unmodulated
luminescence of the green luminescence in bulk. The line labeled ‘exp.’ shows the experimental µ-PL spectrum of the
investigated nanopillar. The experimental spectra recorded for TM- and TE-polarization, respectively, are shown in the
lowest two curves. The curve labeled ‘theory’ displays the theoretical luminescence spectra. Dashed vertical lines are
guides to the eye referring to the spectral position of the dominating WGMs. The inset shows a SEM image of the
investigated pillar, the scale bar has a length of 500 nm. The dotted lines show the position of the edges of the hexagonal
resonator obtained from topography contrast
(a)
(b)
(c)
Fig. 19.31 a Photoluminescence spectra of a ZnO microwire with hexagonal cross section for various pump power
densities (lowest curve: D = 60 kW/cm 2 , top curve: D = 250 kW/cm 2 ) at T = 10 K. The inset shows the scanning
electron microscopy image of a typical microwire (d = 6.40 µm). b Dependence of the emitted PL intensity of a selected
lasing peak (denoted by an arrow in the spectrum in part (a)) on the excitation density D. Lines are guide to the eye.
c Dependence of the resonant energies on the interference order N for wires with different diameters as labeled on top of
the graph. Lines are the predicted theoretical values calculated from (19.59) using diameter values obtained from SEM
measurements; the symbols represent the experimentally observed peaks. Adapted from [1660]
19 Dielectric Structures
(a)
(b)
(c)
(d)
(e)
Fig. 19.30 Simulated near-field intensity pattern of modes in a cavity with hexagonal cross section (absolute value of
electric field in linear grey scale): Modes (N = 4) with (a) symmetry −a and (b) mode 4+ (nomenclature from [1659])
for n = 2.1 and k R = 3.1553 − i0.0748. Modes (c) 26− and (d) 26+ for n = 1.466 and k R = 22.8725 − i0.1064. The
displayed modes have a chiral pattern. Emission originates mostly from the corners. e Micro-photoluminescence spectra
of a single ZnO nanopillar. The three topmost curves are unpolarized. The curve labeled ‘bulk’ shows the unmodulated
luminescence of the green luminescence in bulk. The line labeled ‘exp.’ shows the experimental µ-PL spectrum of the
investigated nanopillar. The experimental spectra recorded for TM- and TE-polarization, respectively, are shown in the
lowest two curves. The curve labeled ‘theory’ displays the theoretical luminescence spectra. Dashed vertical lines are
guides to the eye referring to the spectral position of the dominating WGMs. The inset shows a SEM image of the
investigated pillar, the scale bar has a length of 500 nm. The dotted lines show the position of the edges of the hexagonal
resonator obtained from topography contrast
(a)
(b)
(c)
Fig. 19.31 a Photoluminescence spectra of a ZnO microwire with hexagonal cross section for various pump power
densities (lowest curve: D = 60 kW/cm 2 , top curve: D = 250 kW/cm 2 ) at T = 10 K. The inset shows the scanning
electron microscopy image of a typical microwire (d = 6.40 µm). b Dependence of the emitted PL intensity of a selected
lasing peak (denoted by an arrow in the spectrum in part (a)) on the excitation density D. Lines are guide to the eye.
c Dependence of the resonant energies on the interference order N for wires with different diameters as labeled on top of
the graph. Lines are the predicted theoretical values calculated from (19.59) using diameter values obtained from SEM
measurements; the symbols represent the experimentally observed peaks. Adapted from [1660]