Open-Space Optical Communications Has Possibilities

When we speak about lasers, we often think about material processing, or imaging or military applications, but most lasers in terms of volume are used in communication applications, and its that low-cost, high-speed communications that has driven the entire Internet boom that we all enjoy today.

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When we speak about lasers, we often think about material processing, or imaging or military applications, but most lasers in terms of volume are used in communication applications, and its that low-cost, high-speed communications that has driven the entire Internet boom that we all enjoy today. When you think about it, it wasn’t THAT long ago when we had to use audio phone modems to connect our computers at “amazing” 56K speeds.

While we have long since transitioned to fiber communications for the majority of long-haul communications, we have relied heavily on RF communications for our shorter-range communications needs. Bluetooth, Zigbee, Wi-Fi, and cellular communications all play a part to connect us over shorter distances, and some of these technologies have evolved to faster and faster speeds by moving to higher and higher RF spectrum. The latest 5G (generation) cellular technology which is currently in the testing phase, could offer speeds of up to 10 Gbps and uses RF spectrum around 6 GHz. The characteristics of these high-RF bands is that they can carry large amounts of data at superfast speeds, but the downside is the RF energy can generally only travel shorter distances, and generally line-of-sight. In other-words, as RF frequencies increase toward the frequency of light, the RF starts to take on the characteristics of light. (The transition from RF microwaves to deep IR light occurs at around 300 Ghz.)

While RF and light remain fundamentally different, they both share the ability to transmit large amounts of data, and because of this, light more and more is crossing-over into the realm of what use to be the domain of RF. For example, take Li-fi.

Li-fi is a means of transmitting two-way short-range data by modulating the light from modified lighting fixtures. The first full office designed for Li-fi is expected to open this year. It’s the 37,700 Sq. Ft. offices of Sogeprom's headquarters in Paris and it was installed by the London company PureLiFi. PC’s fitted with special Li-fi dongles communicate with specially modified LED light fixtures in the ceiling. The data speeds achieved are approximately 10 Gbit/sec. but in the lab much higher Li-fi speeds have been achieved.

The Li-fi standard is only a few years old, but support for it is growing quickly. Apple is reportedly testing the technology so that it can be incorporated into a future iPhone, and this is only logical. Incorporating optical communication technologies into devices like phones can be very inexpensive, and offers wireless operators an inexpensive way to off-load data from congested RF bands to unused optical space. Apple would use the image sensor on the iPhone as the receiver so no added hardware costs for the receiver are required, and the transmitter could be a simple IR LED. Overall added costs are very minimal.

Li-fi communications is only one type of optical communications that phone manufacturers are exploring. In fact Apple recently patented a means of blocking iPhone camera recording when the image sensor on a phone picks up a coded IR signal which would be transmitted at a live concert or during a movie. This IR coded signal would instruct the camera in the phone to deactivate.

I believe we are just at the very beginning of multitude of uses for short-range optical communications. For example, perhaps movie theaters using laser illumination could modulate the laser light to not only convey data that the movie shouldn’t be recorded, but also pass data for the hearing and sight impaired. LED or laser headlights on future self-driving cars could pass data to cars ahead to coordinate actions such as passing.

The possibilities for this technology are really unlimited because the cost of adding this technology to existing devices is very small, and none of the regulations that apply to RF transmissions are apply here. Few rules and cheap, or in other-words, a device manufacturer’s dream come true.

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