A chemical detector for detecting predetermined chemicals. The chemical detector includes an optical fiber and a polymer having a high fractional free volume higher than about 0.1 that clads a length of the optical fiber. The optical fiber is arranged within an optical resonator. The chemical detector further includes a coherent light source that excites the optical resonator and a chemical signature detector that detects a predetermined chemical based upon a change in a resonance attenuation or refractive index of the optical fiber caused by absorption of the predetermined chemical into the high intrinsic microporosity polymer cladding of the fiber.