Developing power-over-fiber communications cable: When total isolation is a good thing

Jan 18, 2012
Titus Appel, left, and Steve Sanderson of Sandia National Laboratories’ mobility analysis and technical assessment division display a first-generation power-over-fiber cable that converts a signal from electrical-to-optical-to-electrical, thus emulating an electrical cable in total isolation.

(PhysOrg.com) -- Sometimes total electrical isolation is a good thing — and that’s the idea behind a power-over-fiber (PoF) communications cable being developed by engineers at Sandia National Laboratories.

It’s common to isolate communications between systems or devices by using fiber optic cables, said Steve Sanderson of Sandia’s mobility analysis and technical assessment division. But when power also is required, sending it down a copper wire can at times be a safety issue, and substituting it with battery power may not be suitable or practical, he said.

Sanderson, Titus Appel and Walter Wrye, a former Sandia intern, are co-inventors of a hybrid cable design that uses fiber to send and regulate optical power to the communications electronics integral to the cable. A patent is pending on the design. 

The developers envision their cable replacing existing copper cables in applications related to safety, such as security, explosives, explosion-proof devices, aviation and medical devices.

“The PoF cable has power limitations,” Sanderson said. “It’s not to be construed as a means to power your house, for example, or handle the high speeds of a computer network.

“But because there are growing needs of low-power sensor/control applications related to safety, having convenient optically generated power available is a tremendous benefit.”

The PoF cable ends resemble a typical copper electrical cable with pin and socket connectors. However, optical interface circuits integrated into the connector housing, called a backshell, provide fiber optic transmission of both data communications and optical power.

To conserve energy, optical power is delivered only on demand, Sanderson said.

“The key issue here is to maintain total electrical isolation from any stray electrical energy and high-voltage electrical surges caused by such things as lightning strikes,” he said.  

 The first-generation PoF cable just delivers optical power to the cable’s internal electronics for data communication between devices. The researchers now are adding the capability to deliver electrical power externally to a connected low-power device, Sanderson said.

In the cable’s current version, the backshell encapsulates circular stacked circuit boards with LEDs coupled to plastic optical fibers for communications, and a laser diode and miniaturized photovoltaic-type cell coupled to the ends of a single glass fiber to deliver optical power.

In the next version, the team plans to use only glass fibers. “Although plastic fiber requires less preparation time than glass, it takes up more room,” Sanderson said.

The team recently tested a PoF low-energy detonator firing cable with fireset electronics built into the backshell. The optically powered fireset embeds a microcontroller that reports such things as detonator resistance, temperature and charging voltages, and receives command messages to fire the detonator. When it’s idle or powered down, the circuitry is designed to short the detonator input leads to prevent unwanted electrical energy from reaching it.

The researchers are working with next-generation microcontrollers, new packaging layouts and new optical devices to reduce the size. Team members also are developing a rugged, production-ready PoF cable and are working to reduce the backshell’s length, decrease the weight and lower costs.

 “One of our ongoing objectives is to reduce the physical size so that it’s more widely used,” said Sanderson.

Explore further: Faradair team determined to make hybrid BEHA fly

Related Stories

Physicists demonstrate a time cloaking device

Jul 18, 2011

Physicists Moti Fridman and colleagues at Cornell University have successfully demonstrated a so-called time cloaking device that is able to “hide” time for 15 trillionths of a second. In a paper published on arXiv, the re ...

Optical Broadband Data Transmission in the Home

Mar 27, 2007

Siemens and Infineon have developed a simple broadband transmission system for use in home networks. The system uses optical polymer cables that can be laid and installed without requiring any special skills. ...

Recommended for you

Faradair team determined to make hybrid BEHA fly

20 hours ago

Aiming to transform their concept into a real success, the Faradair team behind a six-seat Bio-Electric-Hybrid-Aircraft (BEHA) have taken this hybrid aircraft project into a crowdfunding campaign on Kickstarter. ...

How polymer banknotes were invented

Nov 26, 2014

The Reserve Bank of Australia (RBA) and CSIRO's 20-year "bank project" resulted in the introduction of the polymer banknote – the first ever of its kind, and the most secure form of currency in the world. ...

Enabling the hearing impaired to locate human speakers

Nov 26, 2014

New wireless microphones systems developed at EPFL should allow the hearing impaired to aurally identify, even with closed eyes, the location of the person speaking. This new technology will be used in classrooms ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.