We present a topological method for deterministic control of the quality factor(Q)and mode conversion in optical microcavities using an exceptional-point(EP)pair.The transition between super-and subradiant modes is go...We present a topological method for deterministic control of the quality factor(Q)and mode conversion in optical microcavities using an exceptional-point(EP)pair.The transition between super-and subradiant modes is governed by braid-group topology on a two-sheet Riemann surface,enabling path-robust Q-tuning without relying on gain-loss balance,nonlinearity,or non-adiabatic encircling.Full-wave simulations demonstrate more than sixfold Q enhancement at a normalized frequency of kr≈3,with higher gains expected at larger kr.The approach requires only a weak elliptical deformation and an engineered internal loss profile,maintaining compatibility with standard photonic platforms.This EP-pair framework offers a scalable and fabrication-tolerant strategy for reconfigurable microlasers,sensors,and integrated photonic devices.展开更多
Semiconductor microdisk lasers have great potential as low-threshold,high-speed,and small-form-factor light sources required for photonic integrated circuits because of their high-Q factors associated with long-lived ...Semiconductor microdisk lasers have great potential as low-threshold,high-speed,and small-form-factor light sources required for photonic integrated circuits because of their high-Q factors associated with long-lived whispering gallery modes(WGMs).Despite these advantages,the rotational symmetry of the disk shape restricts practical applications of the photonic devices because of their isotropic emission,which lacks directionality in far-field emission and difficulty in free-space out coupling.To overcome this problem,deformation of the disk cavity has been mainly attempted.However,the approach cannot avoid significant Q degradation owing to the broken rotational symmetry.Here,we first report a deformed shape microcavity laser based on transformation optics,which exploits WGMs free from Q degradation.The deformed cavity laser was realized by a spatially varying distribution of deep-sub-wavelength-scale(60 nm diameter)nanoholes in an InGaAsP-based multi-quantum-well heterostructure.The lasing threshold of our laser is one-third of that of the same shaped homogeneous laser and quite similar to that of a homogeneous microdisk laser.The results mean that Q spoiling caused by the boundary shape deformation is recovered by spatially varying nanohole density distribution designed by transformation optics and effective medium approximation.展开更多
基金National Research Foundation of Korea(RS-2023-00211817,RS-2022-NR072395,RS-2025-00515537)Institute for Information and Communications Technology Promotion(RS-2019-Ⅱ190003,RS-2025-02304540)+1 种基金National Research Council of Science and Technology(GTL25011-401)Korea Institute of Science and Technology Information(P25026)。
文摘We present a topological method for deterministic control of the quality factor(Q)and mode conversion in optical microcavities using an exceptional-point(EP)pair.The transition between super-and subradiant modes is governed by braid-group topology on a two-sheet Riemann surface,enabling path-robust Q-tuning without relying on gain-loss balance,nonlinearity,or non-adiabatic encircling.Full-wave simulations demonstrate more than sixfold Q enhancement at a normalized frequency of kr≈3,with higher gains expected at larger kr.The approach requires only a weak elliptical deformation and an engineered internal loss profile,maintaining compatibility with standard photonic platforms.This EP-pair framework offers a scalable and fabrication-tolerant strategy for reconfigurable microlasers,sensors,and integrated photonic devices.
基金National Research Foundation of Korea(2020R1A2C3007327)Samsung Research Funding Incubation Center of Samsung Electronics(SRFC-IT1062-05)Development of Creative Technology for ICT(22ZB1100)。
文摘Semiconductor microdisk lasers have great potential as low-threshold,high-speed,and small-form-factor light sources required for photonic integrated circuits because of their high-Q factors associated with long-lived whispering gallery modes(WGMs).Despite these advantages,the rotational symmetry of the disk shape restricts practical applications of the photonic devices because of their isotropic emission,which lacks directionality in far-field emission and difficulty in free-space out coupling.To overcome this problem,deformation of the disk cavity has been mainly attempted.However,the approach cannot avoid significant Q degradation owing to the broken rotational symmetry.Here,we first report a deformed shape microcavity laser based on transformation optics,which exploits WGMs free from Q degradation.The deformed cavity laser was realized by a spatially varying distribution of deep-sub-wavelength-scale(60 nm diameter)nanoholes in an InGaAsP-based multi-quantum-well heterostructure.The lasing threshold of our laser is one-third of that of the same shaped homogeneous laser and quite similar to that of a homogeneous microdisk laser.The results mean that Q spoiling caused by the boundary shape deformation is recovered by spatially varying nanohole density distribution designed by transformation optics and effective medium approximation.
