Optical Sensors Using Ultrahigh-Quality Micro-Resonators

Whispering gallery mode micro-resonators have been used in various sensing applications. They are normally made of melted glass and can have a quality (Q) factor around 10(8). We propose to provide optical gain to the micro-resonator by using erbium ions to increase Q-factor up to 10(9). By controlling pumping and coupling regime we can allow the transmission and dispersive properties of perfectly transparent micro-resonator. For sensor applications, this control would be proportional to the concentration of the element being measured, ensuring high sensitivity.