Patent ID: 7792394

Claim:
A gas analyzer comprising: a light source; an optical fiber optically coupled to said light source, said optical fiber comprising a core and a cladding, said cladding comprising a first plurality of ring-shaped regions defined by high index material having an index of refraction, n h , and a second plurality of ring-shaped regions having a low index of refraction, n l , said first plurality of high index ring-shaped regions having an average thickness, d, and an average periodicity, Λ, said optical fiber further comprising one or more holes in said core or in proximity to said core for receiving a gas, said optical fiber having a sufficient interaction length such that an interaction of said gas with light from said source causes Raman scattering within said fiber and propagation of Raman-scattered light within said optical fiber; and at least one optical detector configured to receive the Raman-scattered light and identify and/or quantify the gas.