Broadband mid-infrared frequency comb generation in a Si_3N_4 microresonator

We demonstrate broadband frequency comb generation in the mid-infrared (MIR) from 2.3 to 3.5 μm in a Si(3)N(4) microresonator. We engineer the dispersion of the structure in the MIR using a Sellmeier equation we derive from experimental measurements performed on Si(3)N(4) films from the UV to the IR. We use deposition-anneal cycling to decrease absorption losses due to vibrational transitions in the MIR and achieve a Q-factor of 1.0×10(6). To our knowledge, this is the highest Q reported in this wavelength range for any on-chip resonator.

• NS
  National Science Foundation

  Award: DGE-0903653
• DA
  Defense Advanced Research Projects Agency

  Awards: W911NF-11-1-0202, BAA-AFOSR-2012-02, W31P4Q-13-1-0016