(CNN) The invention of guns took warfare to a whole new level. Later, airplanes radically changed it again. Now, experts say another big shift is coming, led by energy weapons, including lasers.

The U.S. Air Force Research Laboratory, or AFRL, said it's on track to demonstrate a working laser weapon on a fighter jet by 2020.

"It really is a national tipping point," said Kelly Hammett, chief engineer for the AFRL's directed energy directorate . "We see the technology evolving and maturing to the stage where it really can be used."

Arming larger planes with laser weapons has been possible for years

But the more difficult challenge is to create lasers small, accurate and powerful enough for fighter jets, Hammett said. The g-forces and vibrations of near supersonic speeds make that tough. Hammett said he thinks those hurdles can be overcome within five years.

The AFRL is also working on another idea that sounds like something from "Star Trek":

You might call it a defensive laser shield — as in, "Shields up, Mr. Sulu."

Here's how it would work: A 360-degree laser bubble would surround a U.S. warplane. That bubble would disable or destroy anything that comes inside, like a missile or another aircraft.

To invent such a shield, you'd need a turret that doesn't interfere with the aerodynamics of the warplane. A turret like that has already been successfully tested under Hammett at AFRL in partnership with Lockheed Martin and DARPA, the Pentagon's Defense Advanced Research Projects Agency.

"It's a huge deal," Hammett said.

General: Test in the works using an F-15 Eagle fighter

The test beds for these kinds of weapons likely could be pod units installed aboard so-called fourth generation fighter jets, Hammett said. The commander of Air Force Combat Command, Gen. Herbert "Hawk" Carlisle , revealed last May that a test is in the works involving an F-15 Eagle. "I'm cautiously optimistic that we'll see a prototype test case in the next year or two," Carlisle told Air Combat Command

A mix of laser and conventional weapons could result in "a totally transformed battle space in 20 to 25 years," Hammett said.

Very simply, here's how laser weapons work: They focus extremely concentrated beams of light on their targets, heating them to such high temperatures that they burn or ignite, disabling or destroying the target. Hammett said fighter jet weapons would use a type of laser called solid state -- which creates laser beams by pumping energy into a solid crystalline material.

When researchers and military brass describe these weapons, the operative word is "defensive."

In other words, don't expect to see fighter jets strafing troops with deadly beams of light.

The laser weapons would take out possible threats like enemy vehicles, or disable infrastructure such as cell towers.

When you're shooting a laser, electric power equals ammunition. As long as the plane has fuel to power itself, its laser weapons essentially would be "loaded."

As Hammett put it: "You could have an unlimited magazine ... loitering aircraft that could address and access a wide variety of targets. Incredible precision strike capabilities could be enabled there."

Are laser weapons legal?

There are questions about whether using lasers to attack troops would violate an international treaty called the Protocol on Blinding Laser Weapons. The treaty says : "It is prohibited to employ laser weapons specifically designed, as their sole combat function or as one of their combat functions, to cause permanent blindness to unenhanced vision, that is to the naked eye or to the eye with corrective eyesight devices."

The United States is not the only nation that wants these new laser weapons. "We do know that there are other nations developing similar technologies," Hammett said. "We see research out of near peer countries developing technologies in these areas." He wouldn't say which countries.

More money

But will more money be coming? Rep. Doug Lamborn, R-Colorado, co-chair of the Congressional Directed Energy Caucus, told the Air Force Times in July that laser-armed warplanes may not be a high priority item. He cited "bureaucratic inertia."

Finally, with the Pentagon's widespread use of unmanned aerial vehicles — aka drones — you have to ask: Would the Air Force develop drones with laser weapons systems?

"We're definitely thinking about that," said Hammett.