  We present Near-IR photometry of the Arches cluster, a young and massive
stellar cluster near the Galactic center. We have analyzed the high resolution
(FWHM 0.2") H and K' band images in the Galactic Center Demonstration Science
Data Set, which were obtained with the Gemini/Hokupa's adaptive optics (AO)
system. We present the color-magnitude diagram, the luminosity function and the
initial mass function (IMF) of the stars in the Arches cluster in comparison
with the HST/NICMOS data. The IMF slope for the range of 1.0< log(M/M_sun) <2.1
is estimated to be Gamma = -0.79+/-0.16, in good agreements with the earlier
result based on the HST/NICMOS data [Figer et al. 1999, ApJ, 525, 750]. These
results strengthen the evidence that the IMF of the bright stars close to the
Galactic center is much flatter than that for the solar neighborhood. This is
also consistent with a recent finding that the IMFs of the bright stars in
young clusters in M33 get flatter as the galactocentric distance decreases [Lee
et al. 2001, astro-ph 0109258]. It is found that the power of the Gemini/AO
system is comparable, with some limits, to that of the HST/NICMOS.
