use utf8;
use Encode;
open INPUT,"<:utf8","D:\\try_unicode\\input.txt" or die "Couldn't open file: $!";

close STDOUT;
open STDOUT ,">:utf8","D:\\try_unicode\\output.doc" or die "Couldn't open file: $!";

$unpacking=<INPUT>;
chomp($unpacking);
print "\nunpacking1   :" ,decode("utf8",unpack("x4A4",$unpacking)),"\n";
print "\nunpacking2   :" ,unpack("U4A4",$unpacking),"\n";

close INPUT;
close STDOUT;