TY - JOUR
T1 - Interplay of Leakage Radiation and Protection in Topological Photonic Crystal Cavities
AU - Barczyk, René
AU - Parappurath, Nikhil
AU - Arora, Sonakshi
AU - Bauer, Thomas
AU - Kuipers, Laurens
AU - Verhagen, Ewold
PY - 2022
Y1 - 2022
N2 - The introduction of topological concepts to the design of photonic crystal cavities holds great promise for applications in integrated photonics due to the prospect of topological protection. This study examines the signatures of topological light confinement in the leakage radiation of 2D topological photonic crystal cavities. The cavities are implemented in an all-dielectric platform that features the photonic quantum spin Hall effect at telecom wavelengths and supports helical edge states that are weakly coupled to the radiation continuum. The modes of resonators scaling down to single point defects in the surrounding bulk lattice are characterized via spectral position and multipolar nature of the eigenstates. The mode profiles in real and momentum space are mapped using far-field imaging and Fourier-spectropolarimetry, revealing how certain properties of the cavity modes reflect on their origin in the topological bandstructure. This includes band-inversion-induced confinement and inverted scaling of mode spectra for trivial and topological defect cavities. Furthermore, hallmarks of topological protection in the loss rates are demonstrated, which are largely unaffected by cavity shape and size. The results constitute an important step toward the use of radiative topological cavities for on-chip confinement of light, control of emitted wave fronts, and enhancement of light–matter interactions.
AB - The introduction of topological concepts to the design of photonic crystal cavities holds great promise for applications in integrated photonics due to the prospect of topological protection. This study examines the signatures of topological light confinement in the leakage radiation of 2D topological photonic crystal cavities. The cavities are implemented in an all-dielectric platform that features the photonic quantum spin Hall effect at telecom wavelengths and supports helical edge states that are weakly coupled to the radiation continuum. The modes of resonators scaling down to single point defects in the surrounding bulk lattice are characterized via spectral position and multipolar nature of the eigenstates. The mode profiles in real and momentum space are mapped using far-field imaging and Fourier-spectropolarimetry, revealing how certain properties of the cavity modes reflect on their origin in the topological bandstructure. This includes band-inversion-induced confinement and inverted scaling of mode spectra for trivial and topological defect cavities. Furthermore, hallmarks of topological protection in the loss rates are demonstrated, which are largely unaffected by cavity shape and size. The results constitute an important step toward the use of radiative topological cavities for on-chip confinement of light, control of emitted wave fronts, and enhancement of light–matter interactions.
KW - cavities
KW - Fourier spectroscopy
KW - photonic crystals
KW - quantum spin Hall effect
KW - topology
UR - http://www.scopus.com/inward/record.url?scp=85133280714&partnerID=8YFLogxK
U2 - 10.1002/lpor.202200071
DO - 10.1002/lpor.202200071
M3 - Article
AN - SCOPUS:85133280714
SN - 1863-8880
VL - 16
JO - Laser and Photonics Reviews
JF - Laser and Photonics Reviews
IS - 9
M1 - 2200071
ER -