固体物理セミナー 平成26年度 第9回
Time: 13:00-14:30, 8th (Mon) Dec., 2014
Place: B103 (1F of Buld. B, Graduate School of Engineering Science)
Lecturer: Sahin Kaya Ozdemir 特任教授
Title：「Physics and Applications of Whispering-Gallery-Mode Optical Microcavities」
abstract: Whispering-Gallery-Mode (WGM) optical microcavities with their high-quality factors and microscale mode volumes enables strong light-matter interactions and thus have emerged as versatile platforms for exploring basic science and for fabricating functional devices.In this talk,I will briefly review WGM resonators and introduce their Physics and applications. In particular I will focus on (1) detection of very small nanoparticles (below 10 nanometers in size) using WGM microresonators and microlasers, and (2) on-chip control of optical processes and light transmission in systems of coupled WGM resonators (WGMRs). WGMRs represent open physical systems that are characterized by non-Hermitian Hamiltonians, and thus by appropriately steering the system parameters, their complex eigenvalues and the corresponding eigenstates can be made to coalesce giving rise to a degeneracy referred to as Exceptional point (EP). I will present two applications enabled by driving coupled WGM microcavities through exceptional points. First I will show parity-time (PT) symmetry and its breaking in a system composed of two coupled WGM microcavities, one of which has passive loss (passive resonator) and the other has optical gain (active resonator) balancing the loss of the other. By controlling the inter-cavity coupling strength, one can drive the system from PT-symmetric phase to the broken PT-symmetry phase through an EP. The broken phase enables localization of light in the active resonator, leading to nonlinearity-based nonreciprocal light transmission (optical diode). Then I will show that modulating the loss contrast between two coupled passive resonators can bring the system to an EP where the total intracavity field intensity increases despite increasing loss. This then helps to control intensity-dependent optical processes by loss modulation without requiring optical gain. I will end the talk discussing some of the opportunities and challenges in the WGM research.
問合先：井元 信之 （基礎工Ｄ棟407号室）