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The future of lighting - What will come after LED?

According to researcher Steven DenBaars LED will be replaced by laser lighting in several years. Laser diodes are even more energy saving than LED diodes.

Jef De Meutter

The first incandescent light bulbs saw the light of day at the end of the 19th century. In the years that followed, compact fluorescent lamps were developed in the search for more energy efficient lighting and at the start of this century, LED lighting began making serious inroads. But what will come after LED? We throw a little bit of light on the subject.

From primitive incandescent bulbs to high-tech LEDs

As the saying goes: "You won't know where you're going if you don't know where you've been." That means that reviewing our past can help us to make estimates about the future.

The lighting revolution went very quickly. In barely 150 years, we have gone from rudimentary incandescent light bulbs to advanced LED lighting.

The first incandescent light bulb was developed in 1854 by Heinrich Göbel. He used a charred bamboo fibre in a vacuum-sealed eau-de-cologne bottle (which prevented the bamboo fibre from burning up). That primitive incandescent bulb had a lifespan of barely 400 lighting hours.

Heinrich Göbel

Heinrich Göbel

 

Later, scientists like Thomas Edison, Alexander Lodygin, Joseph Swan and William David Coolidge went to work to improve the light strength and lifespan of that prototype.

The efficiency of a traditional incandescent light bulb is approximately 10%. That means that a great deal of the energy is lost as heat. For halogen lamps (incandescent light bulbs that use inert gas), the efficiency is between 20% and 25%.

At the end of the 1980s, compact fluorescent lamps came on the market. Those lamps are filled with mercury vapour. When the power goes through this lamp, ultraviolet radiation is generated by the mercury vapour. Ultraviolet radiation is invisible to the naked human eye, so a layer of powder has been placed on the inside of the bulb to convert the UV radiation into visible light. With efficiency rates of approximately 40%, compact fluorescent lamps (CFLs) are much more energy efficient than incandescent bulbs and halogen lamps.

In 1995, the first white LED lamp was developed by Japanese scientist Shuji Nakamura. Since then, we have seen an exponential increase in efficiency. With an average light generation of 50% and a lifespan of 50,000 burning hours, those lamps are an enormous improvement over the first incandescent bulbs.

Shuji Nakamura

Shuji Nakamura

 

The future consists of... lasers!

But there is always room for improvement. So a number of researchers are already looking for the successor to LED lighting. According to Steven DenBaars, a researcher at the University of California at Santa Barbara (UCSB), we will be using lasers in the future.

Laserdiode

Laser diodes are much smaller than LEDs.
Source: Wikipedia.org

A laser diode has a number of important benefits. In the first place, laser diodes are considerably smaller than their LED counterparts. The fact that a laser diode can produce up to 1,000 times as much light for only 2/3 of the energy means that it is even possible to light a complete house using only one laser diode.

How does that work?

Steven DenBaars found the solution in fibre optic cable. Those cables can distribute the light from a laser diode over translucent plastic. That converts the powerful beam of light into a warm, diffuse glow. With only a few laser diodes, you can get light to different rooms.

Laser headlights for BMW

BMW is already using laser lighting in its 'i8' hybrid super automobile. Blue laser lighting is being used for the headlights of that vehicle, in combination with phosphor to generate white light. The result is vehicle lighting that will easily outlast the lifespan of the vehicle itself.

BMWi8 laser headlights

A look at the laser technology in the headlights of the BMW i8.
Source: Spectrum.ieee.org

 

BMW i8 laser headlights

The compact laser lighting adds to the snazzy design of the BMW i8.
Source: Bmw.com

But laser lighting can be used for a veritable arsenal of applications. Work is currently under way to develop laser projection for cinemas. Within only a few years, we may see laser diodes in televisions, smartphones and outdoor advertising panels.

Is lighting evolution going too fast?

As designer Bertjan Pot has said: “the downside is that LED lighting is improving too quickly”. Lighting technology is evolving so quickly that lighting in daily life cannot keep up.

We can illustrate that problem with a look at how LED lights are used. The fact that LED lighting (and also laser lighting) is very compact means that it can be used in any conceivable shape. They are extremely flexible.

Virtually all buildings use connections for traditional bulbs, however, (such as an E27 fitting). In the beginning, the shape of the first LED bulbs was modified, which led to overheating.

With laser lighting, a radical change can be brought into being. As was mentioned above, with only a handful of laser diodes and some fibre optic cable, you can illuminate an entire building. Rather than transporting electricity to a lamp, you transport light to the place where it is needed. Not only is that easier to install, but it is also more energy efficient.

Making that transition will probably take several years. Currently, led lighting has only achieved a small fraction of its potential. We will be able to continue to use those little diodes for a long while to come. But one thing is certain. Our children or grandchildren will be using light in a totally different way.

Led lighting