  We report on a low-noise diode laser oscillator at 972 nm actively stabilized
to an ultra-stable vibrationally- and thermally compensated reference cavity.
To increase the fraction of laser power in the carrier we designed a 20 cm long
external cavity diode laser with an intra-cavity electro-optical modulator. The
fractional power in the carrier reaches 99.9% which corresponds to a rms phase
noise of $\phi^2_\textrm{rms}=1\,\textrm{mrad}^2$ in 10\,MHz bandwidth. Using
this oscillator we recorded 1S-2S spectra in atomic hydrogen and have not
observed any significant loss of the excitation efficiency due to phase noise
multiplication in the three consecutive 2-photon processes.
