Abstract

We have fabricated GaAs-based active microtube ring resonators with single layer of InAs quantum dots (QDs) via rolling up the U-shaped InGaAs/GaAs strained bilayer, and then successfully used them as whispering gallery mode (WGM) liquid sensors. Benefiting from much higher refractive index (RI) of III-V semiconductors than that of silicon oxides and nitrides, 0.03 M (mol/L) concentration change of low salinity NaCl aqueous solutions (concentration range: 0 to 1 M) can be sensed by the as-fabricated QD microtube ring resonators. Correspondingly, a maximum sensitivity of 5000 nm/refractive index unit (RIU) and a detection limit (DL) as low as 10^-5 RIU are achieved during detecting low salinity NaCl solutions, which reveals the great potential of active microtube resonators for liquid sensing.

© 2018 The Author(s)