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].