Optical power meters go wireless

28 Jun 2005

Wireless measurements make it easier to monitor optical networks.

The ability to use a mobile phone to make remote measurements of optical power over the airwaves at distances of up to 1 km is now a reality thanks to an innovative idea from Oz Optics. The Canadian company has launched a range of sensors that exploit wireless technology to enable cable-free measurements of signals in optical fibers.

No cables

Oz Optics’ “Wireless Fiber” sensor head consists of a strand of optical fiber, a photodiode detector and a radio transmitter all integrated into a package the size of a match box. A Bragg grating written into the fiber deflects a tiny portion (about 1%) of the light out of the fiber and onto an InGaAs photodiode where it is measured and then broadcast by a radio transmitter. The user simply equips their PDA, laptop or mobile-phone with a plug-in USB/SDIO wireless receiver to display the power measurement.

Oz Optics offers a communication range from 10 m to 1 km or more by using Bluetooth, Wi-Fi or a high-frequency radio signal respectively. The specification sheets also quote an insertion loss of less than 0.2 dB and the ability to handle optical powers of up 1 W.

According to the firm, by adding optical filters or multiple gratings into the sensor head it is possible to make more complex measurements such as checking a signal’s polarization and wavelength as well as its power.

“The next generation service equipment will allow wireless measurements of power, wavelength or temperature and other parameters,” explained Oz Optics’ CEO Omur Sezerman at the LASER 2005 show in Germany where the “Wireless Fiber” was being demonstrated. “You could have easily hundreds or perhaps even thousands of measurement locations, each of which is individually addressable.”

The attraction of the system is that the “Wireless Fibers” can be left permanently in a network to allow remote automated monitoring. In principle, this means that engineers wishing to monitor a fiber-to-the-home (FTTH) could simply drive around a neighborhood checking the power at various nodes where the “Wireless Fiber” has been installed. Alternatively, the data could be logged at a central location and an alarm sounded if any of measurements fall below a threshold value.

Oz Optics says that the data can be encoded to prevent unauthorized reading. Its long range system operates at a high frequency band that does not interfere with other communications and does not require a license.

Author
Oliver Graydon is editor of Optics.org and Opto & Laser Europe magazine.