To provide some context..
I have designed an interstellar spacecraft called Solar One.
It employs a combination of 3 propulsion methods: nuclear fusion, beam-powered propulsion , and photon propulsion.
Basically, several compact fusion reactors power a laser system that propels a huge light sail.
Physicist Robert Forward already proposed in 1983 to use a 26-TW laser system to propel a 100-km light sail, a fresnel lens to focus the beam of the laser, and decelerate the spacecraft with a secondary light sail.
I propose something a bit different, which is to use to use his 26 TW-laser to propel a 1-mile light sail that would deploy from the spacecraft after the acceleration stage, use parabolic mirrors that gradually change their orientation in order to focus the laser beam, and finally use a photon rocket and Bussard scoop to decelerate the spacecraft.
In theory, it could be possible to achieve 22% the speed of light, reaching the closest potentially habitable exoplanet in less than 20 years.
The problem is that high energy lasers weight too much. And a on-board laser would be needed to ionize hydrogen.
What do you guys suggest to reduce their weight?