I did some ballpark calculations on the subject. You would need about 800kW laser to reach parity with M61 Vulcan autocannon. I compared how much you need to m

I did some ballpark calculations on the subject. You would need about 800kW laser to reach parity with M61 Vulcan autocannon. I compared how much you need to melt aluminum with how big volume dent you can make to steel with 20mm round traveling 1000m/s. The energy you need to melt aluminum is considerable, and autocannons have pretty whopping rates of fire. You need 0,05 second beam on target with 30kW laser to have the effect of single 20mm round. During that time M61 fires 5 rounds and incoming BrahMos missile would travel 50 meters. You can claim that penetration is hardly needed. Then you can add bursting charges with programmable time fuses to those 20mm rounds. And you have high speed high accuracy shotgun. It boils down to targeting. Both can do it if they hit in the appropriate time window. BrahMos does S-manouver at the close in range, but 500m before impact it moves straight. At this point it's trajectory is ballistic enough to hit anyhow. And it's kinetic energy is going to give you a bad day no matter what (~1000m/s and ~1ton weight, comparable shell from main gun of Iowa). During that S-maneuver you have to score or you're dead. Cannon rounds have long time of travel, you have to shoot when the missile is 2km away to hit it 1km away. The good news is that missile traveling that fast has to have turn radius of several kilometers. In the future both close in possibilities are likely to be futile. BrahMos II has twice the speed and it's likely to have some stealth features. If you can't see it on radar, shooting it with laser is impossible. You can still see it on IRST, but shooting extremely hot beam of light towards it is going to fuck up your delicate sensors. Edit: current best weaponized lasers have similar size, weight and range than M61. But lot less power. Increasing the range and the power at the same time is very tricky.