TY - JOUR

T1 - Control of mode anticrossings in whispering gallery microresonators

AU - Werner, Christoph S.

AU - Sturman, Boris

AU - Podivilov, Evgeniy

AU - Manjeshwar, Sushanth Kini

AU - Buse, Karsten

AU - Breunig, Ingo

PY - 2018/1/22

Y1 - 2018/1/22

N2 - Optical microresonators attract strong interest because of exciting effects and applications ranging from sensing of single atoms and molecules to quantum and nonlinear optics. For all this, control and tuning of the discrete resonances are vital. In resonators made of anisotropic materials that are beneficial for nonlinear-optical applications, anticrossings of ordinarily (o) and extraordinarily (e) polarized modes occur regularly. This effect is badly understood and harmful for mode control and tuning. We show that the anticrossings are inherent in the o- and e-modes because of the vectorial properties of Maxwell's equations. Within a novel pertubative approach employing a strong localization of the modes near the resonator rim, we have quantified the anticrossings. The values of avoidance gaps strongly exceeding the linewidths and selection rules for the interacting modes are predicted. The inferred values of the avoidance gaps are confirmed experimentally in resonators made of lithium niobate. Furthermore, based on theory, we have eliminated the anticrossings completely by spatially-controlled introduction of defects. This paves the way for unperturbed tuning of anisotropic microresonators.

AB - Optical microresonators attract strong interest because of exciting effects and applications ranging from sensing of single atoms and molecules to quantum and nonlinear optics. For all this, control and tuning of the discrete resonances are vital. In resonators made of anisotropic materials that are beneficial for nonlinear-optical applications, anticrossings of ordinarily (o) and extraordinarily (e) polarized modes occur regularly. This effect is badly understood and harmful for mode control and tuning. We show that the anticrossings are inherent in the o- and e-modes because of the vectorial properties of Maxwell's equations. Within a novel pertubative approach employing a strong localization of the modes near the resonator rim, we have quantified the anticrossings. The values of avoidance gaps strongly exceeding the linewidths and selection rules for the interacting modes are predicted. The inferred values of the avoidance gaps are confirmed experimentally in resonators made of lithium niobate. Furthermore, based on theory, we have eliminated the anticrossings completely by spatially-controlled introduction of defects. This paves the way for unperturbed tuning of anisotropic microresonators.

KW - POLARIZATION CONVERSION

KW - RESONATORS

KW - DISPERSION

KW - WAVE

UR - http://www.scopus.com/inward/record.url?scp=85040961543&partnerID=8YFLogxK

U2 - 10.1364/OE.26.000762

DO - 10.1364/OE.26.000762

M3 - Article

C2 - 29401956

AN - SCOPUS:85040961543

VL - 26

SP - 762

EP - 771

JO - Optics Express

JF - Optics Express

SN - 1094-4087

IS - 2

ER -