Study of Noise Transfer in Semiconductor Frequency Combs

For frequencies well below the relaxation frequency, the fundamental noise of a Fabry-Perot Q-dash mode-locked laser (FP-MLLD) frequency comb is well modeled by a frequency white noise. As a result, the comb modes shows a Lorentzian shape of widths $\Delta v_{n}$ which follow a parabolic law as a function of mode number $n$ . The width of the narrowest mode $\Delta v_{min}$ results from the noise common to all comb modes. The line shape of the radio frequency (RF) beat note of all modes at the repetition rate $F_{rep}$ is also a Lorentzian of width $\Delta F_{rep}$ that impacts the parabola concavity [1], [2].