  We report a simple technique to suppress high frequency phase noise of a
Yb-based fiber optical frequency comb using an active intensity noise servo.
Out-of-loop measurements of the phase noise using an optical heterodyne beat
with a continuous wave (cw) laser show suppression of phase noise by \geq7 dB
out to Fourier frequencies of 100 kHz with a unity-gain crossing of -700 kHz.
These results are enabled by the strong correlation between the intensity and
phase noise of the laser. Detailed measurements of intensity and phase noise
spectra, as well as transfer functions, reveal that the dominant phase and
intensity noise contribution above -100 kHz is due to amplified spontaneous
emission (ASE) or other quantum noise sources.
