Selective gas sensor

A selective gas sensor, comprising a light source, a sensor chip and a light detector;

• the sensor chip having an optical input and an optical output, where the light source is optically connected with the optical input of the sensor chip;
• the optical output of the sensor chip is optically connected with the optical input of the light detector with ability to guide a light from the light source output, through the sensor chip, to the optical input of the light detector;
• wherein the sensor chip comprises a substrate, an asymmetric Mach-Zehnder interferometer, having an input and an output;
• and a cladding, wherein the asymmetric Mach-Zehnder interferometer includes multiple asymmetrical Mach-Zehnder interferometer structures optically connected in parallel, each having different pores size of the polymer cladding that covers both the reference arm and the measurement arm of each respective Mach-Zehnder interferometer, and has multiple outputs that correspond to each of the Mach-Zehnder interferometer structures outputs;
• wherein the pore sizes of each polymer cladding differ by 0.02 nm to 0.1 nm.