Thermal Gradient Induced Transparency and Absorption in a Microcavity

Generation of electromagnetically induced transparency (EIT) and absorption (EIA) effects in optical cavity systems paves a way for many applications ranging from fundamental physics to various photonic applications, such as analogous quantum interference effects, slow light, and light storage. Here, thermal gradient induced transparency (TGIT) and absorption (TGIA) effects in a single microcavity are proposed and demonstrated. The effects originate from the unique temperature gradient in the axial direction of the functionalized microbottle cavity, which leads to different resonance evolutions for whispering gallery modes with different axial orders. Furthermore, this platform is leveraged as a probe to realize a direct temperature readout from the transmission spectrum via multiple TGIT (TGIA is also applicable)-based photonic barcodes with a high detection resolution of 9 x 10(-4) degrees C. This platform offers a novel, highly efficient, and simple scheme to realize dynamic mode coupling for various applications, such as light storage and temperature detection.