Abstract
Owing to their ability to confine electromagnetic energy in ultrasmall dielectric volumes, micro-disk, ring and toroid resonators hold interest for both specific applications and fundamental investigations. Generally, contributions from various loss channels within these devices lead to limited spectral windows (Q-bands) where highest mode Q-factors manifest. Here we describe a strategy for tuning Q-bands using a new class of micro-resonators, named micro-kylix resonators, in which engineered stress within an initially flat disk results in either concave or convex devices. To shift the Q-band by 60 nm towards short wavelengths in flat micro-disks a 50% diameter reduction is required, which causes severe radiative losses suppressing Q's. With a micro-kylix, we achieve similar tuning and even higher Q's by two orders of magnitude smaller diameter modification (0.4%). The phenomenon relies on geometry-induced smart interplay between modified dispersions of material absorption and radiative loss-related Q-factors. Micro-kylix devices can provide new functionalities and novel technological solutions for photonics and micro-resonator physics.
Highlights
Owing to their ability to confine electromagnetic energy in ultrasmall dielectric volumes, microdisk, ring and toroid resonators hold interest for both specific applications and fundamental investigations
Much interest is focused on two-dimensional whispering-gallery mode (WGM) resonators [1, 2], such as micro-disks [3], rings [4] and toroids [5]; these are chip-integrable and offer a wide spectrum of possible applications ranging from microdisk (μ-disk) lasers [6, 7] to sensing [8]
For active μdisks high Q’s are desirable in spectral windows of maximum material gain; possible resonant mode competition can be overcome with an appropriate tuning of spectral positions of high-Q modes towards the gain band peak, without modifying the free-spectral range (FSR) of resonator modes
Summary
Owing to their ability to confine electromagnetic energy in ultrasmall dielectric volumes, microdisk, ring and toroid resonators hold interest for both specific applications and fundamental investigations. Basic schemes to shift high Q-factors from long to short wavelengths rely on achieving a stronger confinement of WGM modes within the resonator device; this is achieved either by increasing the μ-disk diameter or the thickness, both imposing larger device dimensions. The most striking of these, perhaps, is that their geometry induces a tuning of the Q-factor band of resonator modes towards the stronger material absorption range without degrading highest Q’s.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
