"Raytheon's directed energy group has demonstrated a 20 KW laser that can detonate mortar rounds at 500 meters. It comprises 40 low power lasers bundled together and boresighted but operating without the use of a beam control device. Raytheon plans to upgrade the lasers for longer range anti artillery and anti unmanned aircraft missions. The company also fired a kilowatt class solid state illuminator for the Airborne Laser program more than 50 times, for up to 90 seconds. "
From Aviation Week 15 October
Kilowatt solid state lasers that can stay on for a minute and a half are impressive. The laser must keep it's semiconductor lasing material below 125 C while handling a kilowatt. The efficiency of solid state lasers is that of ordinary LED's, at least 75%. Of the kilowatt of electricity into the device, 750 watts comes out as laser light and only 250 watts goes into heating up the laser. Still, keeping the laser down to approximately boiling water temperature with 250 watts heating it is quite a trick. Perhaps this laser is built up of a number of smaller solid state devices ganged together somehow.