All-pervasive laser diodes

Tech Talk

All-pervasive laser diodes

In the early 1960s, when Robert N Hall and his team at the General Electric Global Research Centre first invented the laser diode, little did they know that they had created a technology that would be used in almost every household. This year, the laser turned 50, marking an important milestone.

Fifty years since its invention, the laser diode is what defines the seamless functioning of many of the technological devices we use in our daily lives. From the construction of our house to the things we use inside our home, all are possible to a great extent due to laser technology. When it comes to construction, laser diodes are instrumental in planning, execution, or even creating land maps.

Today, we don’t think twice when surfing the Internet, scanning channels with our TV remote, listening to a CD or moving more swiftly through the checkout line at the grocery store. All of these common, everyday conveniences were made possible, in large part, by the invention of the diode laser.

Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Fundamentally, lasers work by using energy, either optically or electrically, to excite a material, or gain medium, which then amplifies light. This light is then directed into a cavity (think of it as light sandwiched between two mirrors), where the light bounces back and forth repeatedly causing even more light to be emitted. Different materials can be used to generate this reaction and operate a laser.

A diode laser is simply a type of laser where the gain medium is a semiconductor-material such as gallium arsenide, gallium nitride, or indium phosphide, to name a few. Most of the lasers in our daily lives, from CD players, price code scanners in stores to laser printers, are all laser diodes.

By virtue of being light, its properties like speed, wavelength and polarisation are what have made the applications of a laser diode useful across industries. In fact, they are even considered indispensable in the manufacturing of various product prototypes. From telecommunications to retail, military to law enforcement, healthcare to entertainment, the application of laser technology is all pervasive.

Diodes crucial in making ICs

For example, consider your MP3 or even your HD-DVD players; they all read CDs using laser beams. In fact, today, even an iPod would not be what it is if it wasn’t for this technology. Diodes are key in making the small integrated circuits responsible for the compact size and functioning of the iPod. Lasers are used to make patterns 1,000 times smaller than the diameter of a piece of hair on a person’s head.

The patterns etched on a piece of silicon by lasers allow for the storage and memory on an iPod. At our workplace, many of us have seen the use of laser pointers during presentations. However, there are other applications of this technology which are not always visible. From the laser prints we take to the images we scan, all of these technologies are aided by the laser diode.

Bar code readers supported by laser

At retail stores, if it weren’t for the bar code readers supported by laser, billing products would have been a nightmare for the cashier. It’s the laser technology present within the reader that enables it to convert bar codes into readable data that can be registered automatically, easing the whole process.

Though laser is a light source, the light it emits is different from the normal light we use. Various types of lasers can produce different wavelengths of light, from the infrared range in the visible wavelengths to even the ultraviolet range, thus enabling its use across applications.

Unlike the incandescent light which scatters in all directions and enables us to see things around, a Laser emits a single beam which travels only in one direction with energy that is 1000 times more powerful than that emitted by a typical light bulb. Also, this can travel very long distances at a velocity which enables it to cut through metals or even disable missiles that are being launched.

It is this property of laser that makes it beneficial when it comes to military and law enforcement. The laser rangefinder, a device supported by the diode, is used by the military to estimate the distance from their targets apart from accurately aiming weapons. Even in the case of providing heightened security many deploy laser lights to prevent unauthorised entry.

Applications in medicine

In the field of medicine itself, we are all aware of laser treatment or surgery. From laser eye correction to terminating cancerous growths within the human body, this technology has revolutions the process of aiding treatment.

Laser enables bloodless/ non invasive surgery  which considerably lowers the risk of post surgery infectons. In case of invasive surgeries, laser scalpels are also used to control bleeding. As opposed to conventional surgery, laser surgeries also aid faster recovery since they are superficial. This technology is also largely responsible for many of the compact sized portable medical equipments that are available in the market.

On the lighter side, people resort to laser treatment for cosmetic purposes as well. The most commonly known applications are permanent hair removal and scar reduction. The heat of the sharp beam emitted by the laser is what destroys the hair follicle delaying its growth where as in case of scar removal, the heat simply evaporates layers of skin as deemed fit by the dermatologist, diminishing the visibility of scars.

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