Currently there is a large amont of money being poured into laser fusion research. The goal of this would be to find a way to initiate fusion using only lasers. Since fusion uses only hyrdrogen and produces helium, it would be by the far the cleanest most desirable form of energy available to us. However, the chances of actually producing a system efficient enough to use as a power source is very unlikely.
What is much more likely is the development of a system that could by used as a trigger in Hydrogen fusion bombs. In case you don't know, fusion needs a huge amount of energy to begin the process. Currently, fusion bombs are set off using a fission bomb trigger. Fission bombs were dropped on Nagasaki and HIroshima. Fusion bombs are approximately 1000 more powerful than those bombs used in 1946. Besides those that died from the blast, thousands more died from radiation poisoning in the following days, and an untold number died due to cancer caused by the radiation. However, all that radiation comes from the process of fission. If a laser triggered fusion bomb could be created, there would be no radioactive fallout.
The question is, would it be ethical to use such a bomb. The assumption would have to made that it would be used on military targets only, as killing civillians would be reprehensible. It would still level many miles of land and kill everyone within miles around, but the land would not be radioactive and uninhabitable for decades later. The radiation poisoning would probably still happen, but to a much lesser extent, and cancer would probably not be upped due to the fact that those exposed to the initial blast of radiation would die of radiation poisoning.
So, would you condone the use of a laser triggered nuclear weapon in certain cases, or do you believe that weapons of mass destruction of any kind are ethically wrong, even in the context of war?