Experimental demonstration of Kerr optical frequency comb generation in a tellurite microsphere

We experimentally demonstrate optical frequency comb generation in a tellurite microsphere, for the first time to the best of our knowledge, for tellurite glass microresonators. The TeO₂-WO₃-La₂O₃-Bi₂O₃ (TWLB) glass microsphere has a maximum Q-factor of 3.7 × 10⁷, which is the highest ever reported for tellurite microresonators. We obtain a frequency comb containing seven spectral lines in the normal dispersion range when pumping the microsphere with a diameter of 61 µm at a wavelength of 1.54 µm.