**5. Conclusion**

Twisted light beams carrying an orbital angular momentum (OAM) have since been used to build optical tweezers, which use laser light to trap microscopic particles and control their movements. Instead of merely pushing or pulling at the particles, an OAM laser works like a tiny wrench that can torque objects around. In recent years, engineers have built ever smaller OAM beams—some barely as wide as a human blood cell—in the hopes of using them to drive microscale gears and even nanotech machiner. Biomedical diagnostic devices built on a single silicon chip could use such twisted light to operate microscopic equipment or detect the flow and viscosity of minuscule amounts of liquids. Because twisted light is so unusual, it can excite atoms and molecules into odd states not often seen in nature. Electrical engineer Natalia Litchinitser of the University at Buffalo in New York and her colleagues have used metamaterials—synthetic composites that exhibit properties not found in natural materials—to squeeze an OAM beam so that it is only a few nanometers

**37**

**Figure 14.**

**Figure 15.**

*Structured Light Fields in Optical Fibers DOI: http://dx.doi.org/10.5772/intechopen.85958*

wide. Using such beams, they hope to stimulate atoms and molecules into energy states that are extremely difficult to achieve naturally. When the molecules fall back to their ground states, they release characteristic flashes of light, which Litchinitser says could be useful in new kinds of spectroscopic analysis, for instance teasing out

*Twisted light sending data through an optical fiber (https://spectrum.ieee.org/tech-talk/semiconductors/design/*

*The miniature OAM nano-electronic detector decodes twisted light (image courtesy: RMIT University).*

But perhaps the biggest application of twisted light is optical communications. Recently, physicists have shown that photons are not the only ones with OAM. Pushin et al. have demonstrated that neutrons, which according to quantum mechanics act as both particles and waves, can be converted to possess OAM modes. Even acoustic waves have been induced into OAM modes, allowing them to carry more information. Some researchers have also suggested that sound waves carrying OAM can be used for underwater communication networks. These waves would travel better in water, where light is quickly absorbed otherwise (**Figure 15**).

Using twisted optical beams, one would be able to use Internet at 100 times the current speed. The growing potential of OAM beams has astounded those who work with

the individual components of complex compounds (**Figure 14**).

*twisted-light-sends-data-through-optical-fiber-for-first-time).*

*Structured Light Fields in Optical Fibers DOI: http://dx.doi.org/10.5772/intechopen.85958*

*Fiber Optics - From Fundamentals to Industrial Applications*

pattern to split a twisted laser light into nine separate helical beams and sent them 15 m through the air to a telescope. At the receiving end, this telescope was able to distinguish and read out all the beams simultaneously. The bandwidth of the experiment was not quite high though. A multiplexer and demultiplexer for such twisted or helical beams were presented in a research paper at the Optical Fiber Communication Conference and Exposition, in Los Angeles, in March. The multiplexing device presented in the conference was one with multiple waveguides that were carved onto a single chip. Later, Willner et al., researchers from the University of Southern California, reported a research work related to transfer of data using OAM modes of light in Nature Photonics in 2012. They had used twisted light to transfer data at approx. 2.5 terabits per second over a distance of about 1 m. But twisted beams would need to travel lot farther in order to be used for optical communications. Later, a team in Vienna, in 2014, set a record by sending pixelated images of few famous Austrians by using twisted light. The images were sent to another site in Vienna that was 3 km apart. The researchers used helical beams with four helices or twists, such that a data transfer rate of 4 pixels per second could be

*Wireless communication through twisted light (https://www.rdmag.com/news/2017/10/twisted-light-could-*

The improvements should be welcome news to companies such as Intel and Luxtera, which have been racing to find ways to replace the expensive exotic semiconductors and separate components in most optical communications systems with cheap integrated chips made of silicon. Twisted light arrays could allow com-

Twisted light beams carrying an orbital angular momentum (OAM) have since been used to build optical tweezers, which use laser light to trap microscopic particles and control their movements. Instead of merely pushing or pulling at the particles, an OAM laser works like a tiny wrench that can torque objects around. In recent years, engineers have built ever smaller OAM beams—some barely as wide as a human blood cell—in the hopes of using them to drive microscale gears and even nanotech machiner. Biomedical diagnostic devices built on a single silicon chip could use such twisted light to operate microscopic equipment or detect the flow and viscosity of minuscule amounts of liquids. Because twisted light is so unusual, it can excite atoms and molecules into odd states not often seen in nature. Electrical engineer Natalia Litchinitser of the University at Buffalo in New York and her colleagues have used metamaterials—synthetic composites that exhibit properties not found in natural materials—to squeeze an OAM beam so that it is only a few nanometers

**36**

achieved (**Figures 12** and **13**).

*illuminate-new-path-wireless-communications).*

**5. Conclusion**

**Figure 13.**

munication channels between chips in a computer.

#### **Figure 15.**

*Twisted light sending data through an optical fiber (https://spectrum.ieee.org/tech-talk/semiconductors/design/ twisted-light-sends-data-through-optical-fiber-for-first-time).*

wide. Using such beams, they hope to stimulate atoms and molecules into energy states that are extremely difficult to achieve naturally. When the molecules fall back to their ground states, they release characteristic flashes of light, which Litchinitser says could be useful in new kinds of spectroscopic analysis, for instance teasing out the individual components of complex compounds (**Figure 14**).

But perhaps the biggest application of twisted light is optical communications. Recently, physicists have shown that photons are not the only ones with OAM. Pushin et al. have demonstrated that neutrons, which according to quantum mechanics act as both particles and waves, can be converted to possess OAM modes. Even acoustic waves have been induced into OAM modes, allowing them to carry more information. Some researchers have also suggested that sound waves carrying OAM can be used for underwater communication networks. These waves would travel better in water, where light is quickly absorbed otherwise (**Figure 15**).

Using twisted optical beams, one would be able to use Internet at 100 times the current speed. The growing potential of OAM beams has astounded those who work with

them and surprised those who first imagined their possibility. "At one time it was just a fun idea," says Spreeuw. "I could never suspect it would grow into such an industry."
