Ammonia optical sensing by microring resonators

A very compact (device area around 40 mu m(2)) optical ammonia sensor based on a microring resonator is presented in this work. Silicon- on- insulator technology is used in sensor design and a dye doped polymer is adopted as sensing material. The sensor exhibits a very good linearity and a minimum detectable refractive index shift of sensing material as low as 8x10(-5), with a detection limit around 4 parts per thousand.