I hope an optics person can weigh in here for a detailed tech response. In essence if the laser was perfectly parallel it could then be focussed down to a point image as small as the source. How to get a true point - the fiber gradient is all I can think of - and that might have limits. Then adding power - at some point there will be a limit. Even a beam 10 seconds long is a long way in terms of a small beam spread. True, you can waste power, amplify the beam to 100x the power needed might work. Then can the chip withstand this power level at the start? Strange things happen at the atomic level at these power levels - some people feel it may be able to change how atoms decay = accelerate the decay of nuclear waste if the waste is first fractionated to pure radionucleotides first - of course if we did that the storage needs would shrink dramatically, obviating a lot of the problem - my guess is $$ is one barrier?
