Small form factor spectrally selective absorber with high acceptance angle for use in gas detection

A method for gas detection comprising:

• providing a gas sealed in a cavity of an electromagnetic radiation detection device;
• directing radiative power from a light source through one or more target gases and through a cell body of the electromagnetic radiation detection device toward the cavity and a wavelength selective absorber of the electromagnetic radiation detection device, wherein the one or more target gases are located between the light source and the cavity;
• reflecting, with a ring reflector, the radiative power through the one or more target gases and through the cell body of the electromagnetic radiation detection device toward the cavity and the wavelength selective absorber of the electromagnetic radiation detection device;
• setting wavelength sensitivity with the wavelength selective absorber, wherein the wavelength sensitivity is irrespective of an angle of incidence;
• absorbing the radiative power by the wavelength selective absorber and by the one or more target gases;
• detecting, by a pressure sensing element, a pressure change caused by the absorbing of the radiative power;
• and
• determining the one or more target gases based on the detected pressure change.