Heterodyne photonic integrated circuit for absolute metrology

A method for measuring a distance between a digital measuring device and an object, the method comprising:

• producing a first frequency comb of light using a first ring resonator of the digital measuring device;
• directing at least a portion of the first frequency comb of light at the object using the first ring resonator;
• combining a reference beam and light reflected from the object to produce a measurement beam;
• splitting the measurement beam into a plurality of channels spaced in frequency using a first multiplexer of the digital measuring device;
• and
• measuring the distance between the digital measuring device and the object based on the plurality of channels.

A digital measuring device, the digital measuring device comprising:

• a laser source configured to provide light;
• a first ring resonator configured to produce a first frequency comb of light from the light provided by the laser source;
• a local oscillator configured to provide a reference beam;
• at least one waveguide structure configured to combine the reference beam with light reflected from an object to produce a measurement beam;
• a multiplexer configured to split the measurement beam into a plurality of channels spaced in frequency;
• and
• a plurality of detectors configured to detect an intensity value of each channel of the plurality of channels, the intensity value of each channel of the plurality of channels corresponding to a distance between the digital measuring device and the object.