Researchers have transmitted a stable frequency more than 300 kilometers over a standard fiber optic telecommunications network, synchronizing a pair of radio telescopes, according to the Optical Society. The telecom fiber radio astronomy demonstration shows the important role that the fiber could play.
Telecom Fiber Radio Astronomy
Typically, stable frequency references are used to calibrate clocks and instruments that make ultraprecise measurements. The references are usually only accessible at facilities that generate them using expensive atomic clocks. The new technology could enable scientists anywhere with access to a telecommunications network to use the high frequency standard.
The ability to send stable frequency references over the telecommunications network could be particularly useful for radio telescope arrays such as the Square Kilometer Array (SKA), an international effort to build the world’s largest radio telescope using arrays in Australia and South Africa. When complete, SKA will detect faint radio waves from deep space with a sensitivity about 50 times greater than that of the Hubble telescope. Individual radio telescopes will be linked to create a total collecting area of about 1 million square meters.
Linking radio telescopes in an array requires that each telescope have access to an atomic clock to record the precise time at which a signal is detected from an object in space. Focusing all the telescopes on the same object and then calculating the slight differences in the time for the signal to reach each telescope allows researchers to combine all the observations and pinpoint the object’s location and other characteristics.
“By running the experiment on optical fibers also carrying normal traffic, we showed that transmitting the stable frequency standard doesn’t affect the data or telephone calls on the other channels,” said Kenneth Baldwin, a member of the research team from the Australian National University, in a prepared statement. “This is necessary to gain the cooperation of the telecommunications companies that own these fiber networks.”
The new technique doesn’t require any substantial changes to the rest of the fiber optic network. To keep the frequency stable during transmission, the researchers sent the signal through the network to a destination and then reflected it back. The returning signal was used to determine if any changes occurred so that the signal can be corrected if needed.