Introduction

Photonics is the science and technological application of light particles, or photons with a focus on generation, detection, transmission, and manipulation of photons. Photonics can often be confused with optics, as they are both dealing with light. Optics is a branch of physics concerned with the general behaviors of light. Photonics is a subcategory of optics that focuses on the application of light in science and technology. It often emphasizes the particle-wave duality of light. Photonics as a field arguably started as far back as 300 BCE with Euclid’s Optics, but modern photonics really started in the 1960s with the invention of the laser and has only grown in scope and complexity ever since.

Wave-Particle Duality

Photonics takes advantage of the unique properties of light in order to create innovative solutions to complex problems. In simple terms, light has two “natures:” it can act as a wave or as a particle depending on the scenario. Explanations for this wave-particle duality require a significant detour into the realm of quantum mechanics, but even the top physicists are not entirely agreed on why this phenomenon occurs. However, we can see the phenomenon for ourselves through various experiments, the most famous likely being Young’s double-slit experiment.

Exhibit 1: Young’s Initial Double-Slit Experiment

Young’s experiment not only showed the wave-particle duality of light, but also revealed the strangeness of light’s behavior when observed. When a detector is added to the experiment to see which slit the photons are moving through, the results change depending on whether the detector is one or off.

Exhibit 2: Variation on Young’s Double-Slit Experiment

This behavior has remained unresolved to this day. However, photonics-based technologies typically rely on the particle properties of light, as opposed to the wave properties.

Current Applications of Photonics

Photonics is a varied field that includes a number of different technologies that take advantage of the unique properties of light.

Telecommunications. In telecommunications, photonics is applied through optical fibers. Optical fibers are an answer to the problem posed by the vast scope of modern-day communications. When transmitted through a medium, electricity suffers attenuation, which is the loss of average power over long distances. Power is typically measured in decibels, which is logarithmic and a function of attenuation. Fiber optics runs infrared light through high purity glass or plastic, which causes less attenuation and, due to the wavelength of light, more information in a signal than what is possible with a metallic conductor. Combined with the fact that light moves at around 10 times the speed of electricity, and it is clear why photonics in telecommunications is so significant.

Exhibit 3: Power Attenuation Graph

Clean Energy. One of the more famous examples of photonics is in the green energy industry with the existence of photovoltaic cells in solar panels. With the development of photonics as a field, the effectiveness of solar panels will only continue to grow.

Imaging. Photonics is also the backbone of imaging in medicine. Imaging is essentially mapping points from one plane to points on another. Technologies such as optical coherence tomography (OCT) allow for earlier detection of diseases such as Alzheimer’s and glaucoma.

The Emerging Field of Silicon Photonics

There are a number of emerging technologies in the field of photonics, but one of the ones with potentially the greatest impact on daily life is that of silicon photonics. There’s a burgeoning industry for the combination of silicon integrated circuits and lasers, in the form of silicon photonics. In accordance with Moore’s law, the number of transistors in a microprocessor has been doubling about every two years since 1975.

Exhibit 4

This law remained roughly true for the last five decades or so but coupled with the parallel trend of computers getting physically smaller, we run into a problem. In order to fit in physically smaller machines, computer chips have to also shrink. Since computer chips are shrinking, but the number of transistors in them are increasing, the size of the transistors must decrease. However, this creates problems as we have arguably reached the physical limits for how small the transistors can be while still conducting electricity. Conventional physics state a 5-nanometer threshold is hard, physical limit (for comparison, a human hair is anywhere from 25,000 to 50,000 nanometers thick), but there is work being done to push this limit as far as 1 nanometer.

Exhibit 5: Size Comparison between a human hair and modern transistor shows how the transistor is orders of magnitude smaller than a single strand of human hair

Despite possible engineering fixes, there is a general consensus that we are quickly approaching the limit of the computation power of individual computer chips using conventional methods of manufacturing and design.
Enter silicon photonics, which is meant to sidestep the problem of ever-shrinking silicon chips by replacing them with chips that use light waves produced by lasers. Not only does this avoid the problem of the uncertain behavior of electrons when squeezed at the quantum level, it also takes advantage of the fact that light runs significantly faster and cooler than electronic systems. Most of the promise for photonics in computing is theoretical, but there is promise for a massive revolution in computing in the coming decades through photonics.

Exhibit 6: Example of Photonic Chip Design

Market Outlook

Photonics is a large and varied field, but generally the market for photonics is optimistic. Given both the necessity of photonics in our current world and the number of resources being pooled into R&D in this field, it is no surprise most estimate a significant growth in the photonics market. Globally, the photonics market is expected to reach a value of $1,149.62 billion by 2028, registering a CARG of 7.54% from 2023-2028.

Exhibit 7: Global Photonics Market Outlook (2023-2028)

Conclusion

In conclusion, photonics is a varied field with many current and potential applications from medicine to energy technologies to computing.