Japanese Scientists Fire the Most Powerful Laser On the Planet

Sepa Blackforesta writes: Scientist from University of Osaka claim have fired the world's most powerful laser. The beam was intact for 2-petawatt, pulse lasted just one picosecond. While it produced a huge amount of power, the energy required for the beam itself is equivalent to that needed to power a microwave for two seconds. An associate professor of electrical engineering at Osaka University Junji Kawanaka says “With heated competition in the world to improve the performance of lasers, our goal now is to increase our output to 10 petawatts.”

Comments

Re:disappointing

[ShanghaiBill]

It only lasted for a picosecond...

A petawatt for a picosecond is one kilojoule. That is enough energy to warm a liter of water by 0.24C.

Re:Why does anyone care?

[Noah Haders]

Why should anyone care about the power level, as opposed to the pulse energy?

people who have tattoos should care, for one. the ideal tattoo removal laser has really high instantaneous power but really short pulses. this way you get high power but low energy per pulse.

the tattoo ink breaks down better with higher power lasers because it breaks the bonds holding the ink molecules together. but by keeping the energy per pulse low, you're minimizing the tissue damage since tissue damage grows with the amount of energy absorbed by the skin. when you break up the ink molecules into smaller pieces then the immune system can flush away the bits into your lymph nodes. tattoo is gone!

Re:Why does anyone care?

[umafuckit]

I don't know about those times scales, but femto-second pulsed lasers are damn useful for imaging. Briefly, say the experimenter images green fluorescence. Normally, to get green fluorescence you need to excite with blue light of, say, 450 nm. However, if you can pack enough photons into a short packet then you can also get green fluorescence at about double the wavelength. It's called "two photon absorption" and won a Nobel prize. So you pump in 900 nm light and get back green. The advantage is that longer wavelengths are scattered less by biological tissue and, crucially, the depth of field is much better so there is very little out of focus emitted green light (see image in link). Because the laser scans over the specimen relatively slowly (e.g. a few times a second), you can collect scattered green photons and still assign them back to where they came from. So it's very efficient. Maybe this new laser will all for the process to work efficiently with 3 or even 4 photons.