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The recently released Planck data, emphasize that the background geometry of
inflation is not pure de Sitter, but from the slow variation of Hubble parameter during the
inflationary era, it can be quasi-de Sitter. This motivates us to consider an asymptotic de
Sitter mode function for reconstruction of initial mode and primordial power spectrum of
curvature perturbation. Using Markov Chain Monte Carlo (MCMC) method together with
applying recent observational constraints from the Cosmic Microwave Background (CMB)
data for our parameterized asymptotic initial mode shows some deviation from pure de Sitter
or Bunch-Davies mode. Based on Planck 2015 data release the amplitude of scalar perturbations
in 68% confidence level is 109As = 2:94+0:42
ï¿½???0:42 and deviation from Bunch-Davies
mode is 0:05 ï¿½??? 0:06 . In this parametrization, the CMB power spectrum of our model
shows more red-tilt in comparison with CDM model. Furthermore, we found upper limit
for tensor-to-scaler ratio with different pivot scales r0:05 < 0:059 and r0:002 < 0:006.
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