Whispering gallery modes in deformed hexagonal resonators

Grundmann, Marius; Dietrich, Christof P.

doi:10.1002/pssb.201100159

Cited by 32 publications

(26 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, WGMs are also possible in deformed hexagonal resonators but are more probably not stable. 36 It is expected that stimulated emission of a single WGM can be achieved if the NRs are covered with an efficient optically active region as, e.g., InGaN quantum wells or quantum dots. In combination with a tapered NR, this could lead to a tunable monomode laser.…”

Section: Optical Properties Of Gan Nrsmentioning

confidence: 99%

Controlling morphology and optical properties of self-catalyzed, mask-free GaN rods and nanorods by metal-organic vapor phase epitaxy

Tessarek

Bashouti

Heilmann

et al. 2013

Journal of Applied Physics

View full text Add to dashboard Cite

Ductile relaxation in cracked metal-organic chemical-vapor-deposition-grownA simple self-catalyzed and mask-free approach will be presented to grow GaN rods and nanorods based on the metal-organic vapor phase epitaxy technique. The growth parameter dependent adjustment of the morphology of the structures will be discussed. Rods and nanorods with diameters reaching from a few lm down to 100 nm, heights up to 48 lm, and densities up to 8Á10 7 cm -2 are all vertically aligned with respect to the sample surface and exhibiting a hexagonal shape with smooth sidewall facets. Optical properties of GaN nanorods were determined using cathodoluminescence. It will be shown that the optical properties can be improved just by reducing the Ga precursor flow. Furthermore, for regular hexagonal shaped rods and nanorods, whispering gallery modes with quality factors up to 500 were observed by cathodoluminescence pointing out high morphological quality of the structures. Structural investigations using transmission electron microscopy show that larger GaN nanorods (diameter > 500 nm) contain threading dislocations in the bottom part and vertical inversion domain boundaries, which separate a Ga-polar core from a N-polar shell. In contrast, small GaN nanorods ($200 nm) are largely free of such extended defects. Finally, evidence for a self-catalyzed, Ga-induced vapor-liquid-solid growth will be discussed. V C 2013 AIP Publishing LLC. [http://dx

show abstract

Section: Optical Properties Of Gan Nrsmentioning

confidence: 99%

Controlling morphology and optical properties of self-catalyzed, mask-free GaN rods and nanorods by metal-organic vapor phase epitaxy

Tessarek

Bashouti

Heilmann

et al. 2013

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…WGMs in a hexagonal structure are based on reflections of light either at six or three sidewall facets, designated as hexagonal or triangular WGMs, respectively [14]. In hexagonal cavities consisting of materials having a refractive index > n 2 (with n = 1 outside the cavity), triangular WGMs are dominant because Q-factors by up to two orders of magnitude higher compared to Q-factors from hexagonal WGMs are possible due to strong coupling of superscar modes [15].…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Carrier-induced refractive index change observed by a whispering gallery mode shift in GaN microrods

et al. 2015

View full text Add to dashboard Cite

Vertical oriented GaN microrods were grown by metal-organic vapor phase epitaxy with four different n-type carrier concentration sections above 10 19 cm −3 along the c-axis. In cathodoluminescence investigations carried out on each section of the microrod, whispering gallery modes can be observed due to the hexagonal symmetry. Comparisons of the spectral positions of the modes from each section show the presence of an energy dependent mode shift, which suggest a carrier-induced refractive index change. The shift of the high energy edge of the near band edge emission points out that the band gap parameter in the analytical expression of the refractive index has to be modified. A proper adjustment of the band gap parameter explains the observed whispering gallery mode shift. ExperimentalThe GaN microrod samples were grown by a self-catalyzed vapor-liquid-solid (VLS) method on 2 inch c-plane sapphire substrates utilizing an Aixtron 200RF horizontal flow metal-organic vapor phase epitaxy (MOVPE) reactor [12]. Trimethylgallium (TMGa), silane, hydrogen, and ammonia were used as precursors. Silane is needed for n-type doping and enhances the vertical growth due to the formation of surface SiN acting as a

show abstract

“…However, the finite spatial dimension of the microwires leads to an optical confinement and thus to the formation of energetically separated optical modes, typically Fabry-P erot (FPM) and Whispering Gallery modes (WGM). 16,17 In this case, the photonic density of states is not monotonically increasing and exhibits zeros (or minima) between the optical modes which leads to a suppression of the emission in this energy range. The nature of the optical modes can be distinguished by their dispersion with respect to the wave vector within the wire plane and the energetic mode separation.…”

mentioning

confidence: 99%

“…However, due to the bending of the microwire, the tensile and compressive facets are slightly distorted. 17 Furthermore, the damping of these modes is enhanced compared to an unstrained microwire due to the red shift of the band gap energy at the compressive strained facet.…”

mentioning

confidence: 99%

Non-linear optical deformation potentials in uniaxially strained ZnO microwires

Sturm

Wille

Lenzner

et al. 2017

Applied Physics Letters

View full text Add to dashboard Cite

The emission properties of bent ZnO microwires with diameters ranging from 1.5 μm to 7.3 μm are systematically investigated by cathodoluminescence spectroscopy at T≈10 K. We induced uniaxial strains along the c-axis of up to ±2.9 %. At these high strain values, we observe a non-linear shift of the emission energy with respect to the induced strain, and the magnitude of the energy shift depends on the sign of the strain. The linear and non-linear deformation potentials were determined to be D1=−2.50±0.05 eV and D2=−15.0±0.5 eV, respectively. The non-linearity of the energy shift is also reflected in the observed spectral broadening of the emission peak as a function of the locally induced strain, which decreases with increasing strain on the compressive side and increases on the tensile side.

show abstract

Whispering gallery modes in deformed hexagonal resonators

Cited by 32 publications

References 42 publications

Controlling morphology and optical properties of self-catalyzed, mask-free GaN rods and nanorods by metal-organic vapor phase epitaxy

Controlling morphology and optical properties of self-catalyzed, mask-free GaN rods and nanorods by metal-organic vapor phase epitaxy

Carrier-induced refractive index change observed by a whispering gallery mode shift in GaN microrods

Non-linear optical deformation potentials in uniaxially strained ZnO microwires

Contact Info

Product

Resources

About