All interference gravitational wave detectors, such as LIGO, VIRGO and GEO600, rely on the laser pointer system and need to keep their high output power stable within a year, and their power fluctuations on the time scale are very small. The research team has a world leading position in this research field. They built the laser system GEO600 and advanced LIGO. Without such equipment, it is impossible to directly detect gravitational waves for the first time.
Now, Jonas Junker has further improved the existing power stabilization system in his master's research in Willke's team. A part of the laser beam is removed to achieve multiple distributions of the detector, thereby accurately determining the total power. If it changes, the main laser power is corrected accordingly. In their experiments, the scientists expanded the current system. In addition, another photodetector can also control and correct the direction of the laser beam.
In the Einstein Institute, the improved power stabilization scheme has been successfully applied to a 10-meter prototype interferometer of a 35-watt green laser pointer system. The prototype is a demonstration and test of the technology of the third generation detector by researchers in Hanover, and the quantum mechanical effects of these instruments have been studied. The power stability reaches five times, which is higher than comparable experiments in other groups. This result agrees very well with the results of independent desktop experiments.
"Experiments conducted in an optical laboratory isolated from the outside environment are completely different from large experiments with a 10 meter prototype. We first discovered that it can be transferred from a desktop experiment with excellent stability," Willke Say. "We found that these photodiode arrays work as expected, which means that it should also be able to be used in the same multi-detector array, advanced LIGO, and achieve this high stability."