Time division multiplexing (TDM) and wavelength division multiplexing (WDM) fast-sweep interrogator

An apparatus for interrogating optical elements having characteristic wavelengths spanning a sweep range, comprising:

• an optical waveguide;
• an optical source configured to introduce a pulse of light into the optical waveguide to interrogate multiple sets of optical elements by performing a sweep of wavelengths over a period of the pulse;
• a receiver, wherein:
• within each set, the optical elements have different characteristic wavelengths;
• the light is reflected from the optical elements in each set;
• the period of the pulse over which the sweep of wavelengths is performed, the characteristic wavelengths of the optical elements in each set, and a spacing of the optical elements in each set define a sweep window associated with each set corresponding to a time over which the reflected light in each set is spread;
• and
• a first sweep window associated with a first one of the multiple sets of optical elements is disposed outside a second sweep window associated with a second one of the multiple sets of optical elements;
• and
• a processing system configured to process the reflected light from the optical elements to determine a parameter.

A system for interrogating optical elements having characteristic wavelengths spanning a sweep range, comprising:

• a wellbore,
• an optical waveguide at least partially disposed in the wellbore;
• an optical source configured to introduce a pulse of light into the optical waveguide by performing a sweep of wavelengths over a period of the pulse;
• multiple sets of optical elements disposed along the optical waveguide, wherein:
• within each set, the optical elements have different characteristic wavelengths;
• the light is reflected from the optical elements in each set;
• the period of the pulse over which the sweep of wavelengths is performed, the characteristic wavelengths of the optical elements in each set, and a spacing of the optical elements in each set define a sweep window associated with each set corresponding to a time over which the reflected light in each set is spread;
• and
• a first sweep window associated with a first one of the multiple sets of optical elements is disposed outside a second sweep window associated with a second one of the multiple sets of optical elements;
• and
• a processing system configured to process the reflected light from the optical elements to determine a parameter.