  A fully stabilized soliton microcomb is critical for many applications of
optical frequency comb based on microresonators. However, the current
approaches for full frequency stabilization require either external
acousto-optic or electro-optic devices or auxiliary lasers and multiple
phase-locked loops, which compromises the convenience of the system. This study
explores a compact atomic referenced fully stabilized soliton microcomb that
directly uses a rubidium atomic optical frequency reference as the pump source,
and complements the repetition rate (7.3 GHz) of the soliton microcomb was
phase-locked to an atomic-clock-stabilized radio frequency (RF) reference by
mechanically tuning the resonance of the optical resonator. The results
demonstrate that the stability of the comb line (0.66 THz away from the pump
line) is consistent with that of the Rb87 optical reference, attaining a level
of approximately 4 Hz @100 s, corresponding to the frequency stability of 2E-14
@100 s. Furthermore,the frequency reproducibility of the comb line was
evaluated over six days and it was discovered that the standard deviation (SD)
of the frequency of the comb line is 10 kHz, resulting in a corresponding
absolute deviation uncertainty of 1.3E-10, which is technically limited by the
locking range of the soliton repetition rate. The proposed method gives a
low-power and compact solution for fully stabilized soliton micorcombs.
