Computers were been working on elecricity.. now adays they have use fiber optic to transfer networks.. why don't they use the light or laser to operate the computer since it is faster than the electricity?! I believe it can be done...

They do use Laser for Audio/Video/Data. If mean to power the computer, You could, but don't think it is efficient enough. Not sure about the race between laser and electricity, each may perform faster in their own preferred environment.

IBM is currently exploring that option:
IBM sets sights on faster, efficient "light" chips: News - Hardware - ZDNet Australia

Another key point is that it's very expensive to implement. You need termination at both ends of a fiberoptic cable, plus the cable itself. Right now it's not really worth the extra money for the performance increase you would get, though I'm sure they will find ways to make it cheaper and more efficient.