Optical microresonator based on hollow sphere with porous wall for chemical sensing.

A porous-wall hollow glass microsphere (PW-HGM) was investigated as an optical resonator for chemical vapor sensing. A single mode optical fiber taper was used to interrogate the microresonator. Adsorption of chemical molecules into the nanosized pores induced a refractive index change of the thin wall and thus a shift in its resonance spectrum. The PW-HGM resonator had shown higher vapor detection sensitivity in comparison with a solid microsphere under similar test conditions.