  Until 2004, Anomalous X-ray Pulsars (AXPs) were known as strong emitters of
soft X-rays only (< 10 keV). The discovery of hard X-ray component from AXPs
provided important insight about their emission properties while it posed a
serious challenge to explain its origin. The physical mechanism of the hard
emission component has still not been fully resolved. We investigate the
high-energy gamma-ray properties of the brightest AXP, 4U 0142+61 using data
collected with the Large Area Telescope (LAT) on board Fermi Gamma-ray Space
Telescope to establish the spectral behavior of the source on a very broad
energy span and search for pulsed emission. Here, we present our results of
detailed search for the persistent and pulsed high-energy gamma-ray emission
from 4U 0142+61 which result in no significant detection. However, we obtain
upper limits to the persistent high-energy gamma-ray emission flux which helps
us to constrain existing physical models.
