Extremely complex instruments can observe the oscillations of light directly. However, indirect frequency measurement is possible with frequency combs. Optical frequency combs are light waves composed of a large number of spectral lines spaced at equal distances. Two methods for generating frequency combs are exciting dissipative solitons in lasers or passive resonators. Both these methods suffer from significant limitations.
Now, researchers have combined the advantages of each platform. They hosted a novel kind of soliton (called an active cavity soliton) within coherently driven lasers, pumped below the lasing threshold. The researchers used an active fiber resonator to measure high-peak-power solitons on a low-power background as per simulations of a generalized Lugiato–Lefever equation.
The findings of this research reveal that amplified spontaneous emission has a negligible impact on the soliton’s stability. The combination of coherent driving and incoherent pumping can be efficiently combined to generate a high-power ultra-stable pulse train. The results open up novel avenues for frequency comb formation.