Frequency comb stabilization using combined detection

A method for generating a frequency comb spectrum, the method comprising:

• combining a plurality of optical signals at a photodetector, the plurality of optical signals comprising:
• a first optical spectrum generated using a spectrum broadening optical component that receives an optical pulse output from a frequency comb oscillator;
• a second optical spectrum generated using a frequency doubling optical component that receives one of:
• the optical pulse output from the frequency comb oscillator or the first optical spectrum;
• and
• a third optical spectrum received from a frequency-stabilized optical reference;
• in response to combining the plurality of optical signals at the photodetector, producing an electrical signal comprising multiple heterodyne signals at respective frequencies;
• generating a first error signal based on a first heterodyne signal in the multiple heterodyne signals, the first heterodyne signal determined based on the first optical spectrum and the second optical spectrum;
• generating a second error signal based on a second heterodyne signal in the multiple heterodyne signals, the second heterodyne signal determined based on the first optical spectrum and the third optical spectrum;
• and
• generating, from the frequency comb oscillator, a frequency comb spectrum comprising a pulse train output at a repetition rate, wherein the first error signal is input to the frequency comb oscillator to stabilize a carrier-offset frequency of the frequency comb spectrum, and the second error signal is input to the frequency comb oscillator to stabilize a spectral component of the frequency comb spectrum.

A frequency comb system, the system comprising:

• a frequency comb oscillator configured to:
• receive a first RF signal that stabilizes a carrier offset frequency of a frequency comb output by the frequency comb oscillator;
• receive a second RF signal that stabilizes a spectral component of the frequency comb;
• and
• output an optical pulse at a repetition rate stabilized by the frequency-locked carrier offset frequency and the frequency-locked spectral component;
• an optical reference having a frequency-stabilized continuous wave optical output;
• a non-linear optical component comprising:
• a spectrum broadening optical component that receives an optical pulse output from the frequency comb oscillator and outputs a first optical spectrum;
• and
• a frequency-doubling optical component that outputs a frequency-doubled spectrum based on an input spectrum, wherein the input spectrum is one of:
• an optical pulse from the frequency comb oscillator or the first optical spectrum;
• a photodetector configured to:
• receive the first optical spectrum, the frequency-doubled spectrum and the continuous wave optical output, in response to which the photodetector produces an RF electrical signal comprising:
• a first heterodyne signal produced from mixing the first optical spectrum and the frequency-doubled spectrum at the photodetector;
• and
• a second heterodyne signal produced from mixing the first optical spectrum and the continuous wave optical output at the photodetector;
• and
• an electronic control circuit, coupled to the photodetector to receive the first heterodyne signal and the second heterodyne signal, the electronic control circuit comprising:
• a first error determination circuit, configured to generate the first RF signal;
• and
• a second error determination circuit, configured to generate the second RF signal.