  We propose an alternative scheme for phase estimation in a Mach-Zehnder
interferometer (MZI) with photon recycling. It is demonstrated that with the
same coherent-state input and homodyne detection, our proposal possesses a
phase sensitivity beyond the traditional MZI. For instance, it can achieve an
enhancement factor of 9.32 in the phase sensitivity compared with the
conventional scheme even with a photon loss of 10% on the photon-recycled arm.
From another point of view, the quantum Cramer-Rao bound (QCRB) is also
investigated. It is found that our scheme is able to achieve a lower QCRB than
the traditional one. Intriguingly, the QCRB of our scheme is dependent of the
phase shift phi while the traditional scheme has a constant QCRB regardless of
the phase shift. Finally, we present the underlying mechanisms behind the
enhanced phase sensitivity. We believe that our results provide another angle
from which to enhance the phase sensitivity in a MZI via photon recycling.
