Highly stable semiconductor lasers and sensors for III-V and silicon photonic integrated circuits

A chemical sensor comprising:

• a broadband infrared optical source;
• an extended passive sensing waveguide having a first end and a second end and having a top surface exposed to an ambient sample gas or liquid,
• the first end of the extended passive sensing waveguide being coupled to an output of the broadband optical source, and
• the second end of the extended passive sensing waveguide being coupled to a multi-spectral detector comprising a plurality of resonant-cavity infrared detectors (RCIDs) aligned in series along the extended passive sensing waveguide,
• wherein each of the RCIDs is bounded by a corresponding set of two distributed Bragg reflector (DBR) mirrors formed by gratings having a predetermined grating pitch etched into the extended passive sensing waveguide,
• wherein the predetermined grating pitch of the two DBR mirrors in each set of DBR mirrors is the same and is different from a grating pitch of any other set of DBR mirrors;
• wherein each RCID has a corresponding resonance wavelength that is different from a resonance wavelength of every other RCID in the series;
• wherein each RCID includes a top electrical contact configured to detect a photocurrent resulting from light flowing in the RCID due to light propagating in the extended passive sensing waveguide;
• wherein the photocurrent flowing in each RCID is sensitive primarily to incoming light having a wavelength within one linewidth of the resonance wavelength of the RCID but is less sensitive to light having a wavelength not within one linewidth of the resonance wavelength of the RCID;
• and
• wherein a total of the photocurrent measured by the plurality of RCIDs provides information about at least one spectral characteristic of light input to the extended passive sensing waveguide.