High-Power Laser May Search for Earth-like Planets
A new laser that is 100 to 1000 times more powerful than typical high-speed lasers could help researchers look for Earth-like planets located billions of miles away.
The laser, which was built by Albrecht Bartels and colleagues at the University of Konstanz in Germany, offers a record-breaking combination of high speeds, short pulses and high average power. Specifically, it emits 10 billion light pulses per second, with each pulse lasting just 40 femtoseconds (quadrillionths of a second). Its average power is 650 milliwatts.
Researchers from the National Institute for Standards and Technology also collaborated on the project, and showed that the laser could give current astronomical tools a 100 times greater sensitivity when searching for planets that orbit distant stars.
When searching for these Earth-like planets, astronomers can look for variations in the color of a star's light, which indicate a planet is orbiting the star. That's because the planet causes small wobbles in the star's motion, and the wobbles shift the frequency and color of the star's light.
Current astronomical instruments can detect a wobble of about 1 meter per second. However, small planets could cause their stars to wobble just a few centimeters per second. Using the new dime-sized laser as a "frequency comb" could greatly improve the sensitivity for detecting frequency variations due to wobbling. The laser could produce a frequency comb with larger gaps between its 25,000 teeth in such a way to make it ideal for these kinds of sensitive astronomical measurements.
Searching for planets with frequency combs is an international endeavor, which involves several major institutions such as the Max-Planck Institute for Quantum Optics in Germany and the Harvard Smithsonian Center for Astrophysics in the US, among others.