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Photonics

Definition: the science and technology of light

Alternative term: lightwave technology

More specific terms: silicon photonics, quantum photonics

German: Photonik

Category: photonic devices

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URL: https://www.rp-photonics.com/photonics.html

Photonics is the science and technology of light, with an emphasis on applications: harnessing light in a wide range of fields. This term photonics was coined by the French physicist Pierre Aigrain in 1967 and is widely used since the mid-1970s. An alternative term is lightwave technology. There is also the term photon science, which relates to the scientific part of photonics.

Light (high-frequency electromagnetic radiation) obviously plays the central role in photonics. The used light encompasses not only visible, but also infrared and ultraviolet light.

At the heart of photonics are technologies for generating light (e.g. with lasers or with light-emitting diodes), transmitting, amplifying, modulating, detecting and analyzing light (e.g. with spectroscopy), and particularly using light for various practical purposes. It thus builds heavily on optical technology (→ optics), supplemented with modern developments such as optoelectronics (mostly involving semiconductors), laser systems, optical amplifiers and novel materials (e.g. photonic metamaterials). The scientific basis is mostly within physics, in particular optical physics and related areas such as laser physics and quantum optics.

Typical application areas of photonics are

Photonic key technologies of particular importance are laser and amplifier systems, light-emitting diodes (LEDs) and other non-laser light sources, optical fibers and other waveguides, optical modulators, photodetectors (including cameras), and displays.

There is an analogy with electronics: just as electronics is the utilization of electrons, photonics works on the basis of photons. The quantum (photon) nature of light is often, but by far not always of interest in photonics; there is the more specific area of quantum photonics. This is important for secure communications, and in the future possibly also for quantum computing. A substantial amount of scientific research is still required to enable such advanced applications.

Importance of Photonics

Photonics is considered as one of the key technologies of the 21st century. It supplements electronics in the form of optoelectronics (optronics) and exhibits a strong market growth, which is expected to continue for the foreseeable future. So far, photonics has achieved a deep penetration of mass markets and correspondingly large sales volumes in only a few areas, e.g. laser diodes in CD/DVD players and related technics of optical data storage. Huge growth opportunities are expected from the development of silicon photonics and other technologies for photonic integrated circuits, from LEDs with improved output power and efficiency, or from laser types (e.g. VECSELs) which are suitable for cost-effective mass production.

Various government institutions, including agencies for research funding, have recognized the enormous importance of photonics for science, technology and the whole economy, and thus try to strengthen the development of photonics as an enabling technology:

  • There is the European technology platform Photonics21, which implements a common photonics strategy in the Horizon2020 Public Private Partnership and is expected to have substantial effects on job creation. Many hundreds of million euros per year support photonics research programs in Europe.
  • In the United States, the National Photonics Initiative (NPI) tries to increase collaboration and coordination among the U.S. industry, government and academia, and to identify particularly important areas of photonics which are critical for competitiveness and national security. The report Harnessing Light of the U.S. National Academy of Sciences Light committee has found a lot of attention by analyzing the current state of optical sciences and suggested goals for future developments.
  • China, Japan and South Korea are also investing enormous resources into photonics research. For example, the new Science and Technology (S&T) plan of China does a lot for photonics research and development; of the order of 1 billion euros per year are currently invested into photonics R & D in China.

Nobel Prizes in Photonics

The importance of photonics is also underlined by the substantial number of Nobel Prizes awarded in recent years:

  • 2018: Nobel Prize in Physics awarded to Arthur Ashkin for the invention of optical tweezers and to Gérard Mourou and Donna Strickland for chirped-pulse amplification.
  • 2017: Nobel Prize in Physics awarded to Rainer Weiss, Barry C. Barish and Kip S. Thorne “for decisive contributions to the LIGO detector and the observation of gravitational waves” (→ use of laser interferometers for gravitational wave detection)
  • 2014: Nobel Prize in Physics awarded to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura “for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources” (→ light-emitting diodes)
  • 2014: Nobel Prize in Chemistry awarded to Eric Betzig, Stefan W. Hell and William E. Moerner “for the development of super-resolved fluorescence microscopy” (→ fluorescence microscopy)
  • 2012: Nobel Prize in Physics awarded to Serge Haroche and David J. Wineland “for ground-breaking experimental methods that enable measuring and manipulation of individual quantum systems” (→ quantum optics, laser cooling of atoms, optical frequency standards)
  • 2010: Nobel Prize in Physics awarded to Andre Geim and Konstantin Novoselov “for groundbreaking experiments regarding the two-dimensional material graphene” (which has particularly interesting implications in photonics)
  • 2009: Nobel Prize in Physics awarded to Charles Kuen Kao “for groundbreaking achievements concerning the transmission of light in fibers for optical communication” (→ optical fibers, fiber optics, optical fiber communications) and to Willard S. Boyle and George E. Smith “for the invention of an imaging semiconductor circuit – the CCD sensor”
  • 2005: Nobel Prize in Physics awarded to Roy J. Glauber “for his contribution to the quantum theory of optical coherence” (→ coherence, quantum optics) and to John L. Hall and Theodor W. Hänsch “for their contributions to the development of laser-based precision laser spectroscopy, including the optical frequency comb technique” (→ frequency combs, optical frequency standards, frequency metrology)
  • 2001: Nobel Prize in Physics awarded to Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman “for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates”
  • 2000: Nobel Prize in Physics awarded to Zhores I. Alferov and Herbert Kroemer “for developing semiconductor heterostructures used in high-speed- and opto-electronics” (→ laser diodes) (together with Jack S. Kilby “for his part in the invention of the integrated circuit”, which is outside photonics)
  • 1997: Nobel Prize in Physics awarded to Steven Chu, Claude Cohen-Tannoudji and William D. Phillips “for development of methods to cool and trap atoms with laser light” (→ laser cooling)

Challenges for the Development of Market Penetration of Photonics

New technologies do not automatically reach deep penetration of many markets, because a number of obstacles first have to be overcome.

Competition with Other Technologies

In many cases, a new photonic application is competing with older approaches to solve a problem, just offering more or less substantial advantages, for example in terms of quality of results or speed. It can then be challenging to convince people to switch over to the new technology, with which they are not yet familiar and which may be difficult for them to understand. Early adopters need to be identified and motivated to invest into often time-consuming and expensive tests, and success stories need to be spread in the community until the new technology can gain traction. That process can take many years, even where photonic solutions offer substantial advantages, or may even fail.

Cost and Capital Issues

In many application areas, the progress for market penetration of photonics products is hindered by the problem of high cost. For example, lasers are in most cases rather expensive devices, even when based on not particularly complex technology. The main reasons for that are the following:

  • Due to the short wavelengths of light, optical components often need to be aligned very precisely. Therefore, highly precise opto-mechanics are required, and the alignment procedures can be difficult and time-consuming, as far as they cannot be automated.
  • Although alignment processes can often be avoided by using fiber connectors instead of free-space optics, fiber optics connections are also much more delicate than most electrical connections.
  • Generally, optical setups are highly sensitive to dust, dirt and scratches, so that they need to be made in a very clean environment and handled with great care. (This is also largely due to the short optical wavelengths.)
  • Due to the small production numbers, most lasers and photonic instruments (e.g. optical spectrum analyzers) are fabricated in ways which require substantial amounts of labor. Efficient production methods, as used for example for cars or for electronics, are so far not widely used, because the high initial investment would be worthwhile only for larger production numbers – which however are still hindered by the current product cost.
  • Even though the total production numbers of lasers, for example, have become quite substantial, they are spread over a huge number of different models – not only because they are made by numerous manufacturers, but also because a substantial number of operation parameters has to be adapted to specific applications, having very different requirements. For example, a wide range of laser technologies is needed to cover different combinations of optical wavelength, average power, pulse energy, duration and repetition rate. Note that some of those parameters like pulse duration and pulse energy can vary in wide ranges, spanning multiple orders of magnitude. Therefore, it is generally not possible just to make different variants of a particular kind of laser system.

The more effective solutions are found for those problems, the better are the chances for further economical growth of the photonic sector. For example, VECSEL technology could lead to substantially cheaper replacements for many traditional solid-state lasers (mostly for continuous-wave operation), and silicon photonics could find a lot of applications in mass markets (particularly in information technology) with strong cost pressure.

The production cost after successful market entry is not the only issue; a substantial initial hurdle can be the required capital to do the initial development and penetrate the market. For example, one often requires expensive machinery, which can in the long run be quite cost-competitive due to efficient mass production, but requires substantial investments for the initial development. Since the way from initial investment to successful commercialization can take many years, where substantial surprises may have to be dealt with, it is not easy to acquire the necessary investment capital – also because it is not easy to first develop a complex plan and then convincingly explain it to people not having a precise understanding of the technology at the application.

Very different models are applied in practice to tackle such problems. For example, some large companies regularly devote substantial resources to such new developments, covering the cost with turnover from already established business. In other cases, investors support small startup companies, hoping that their part of the shares will eventually acquire a value which is a multiple of the initial investment. As the potential of photonics is already well known among investors, such approaches have become quite realistic. However, substantial risks remain for all involved – also for the technological initiators, who may end up with a rather small share of the created value.

Niche Markets

A relatively limited number of new photonic applications is in mass markets, for example concerning smartphones or optical fiber communications. Many other photonic applications can only address relatively small markets, using quite specialized technology. For example, a new technology for laser eye treatments or for medical imaging could be expected to be used only in a couple of thousand clinics worldwide, replacing some of the previously existing technology within a couple of years. Therefore, a substantial sales margin is required to make the technology economically viable despite a limited number of sales. The small production volumes also do not allow the utilization of highly cost-efficient techniques of mass fabrication.

Still, addressing such niche markets can work, providing substantial benefits for the society as a whole as well as substantial rewards for the initiators of new companies.

Required Combination of Competencies

The successful establishment of a new photonic technology in a market of substantial size requires a combination of very diverse competencies – not only the technical competence to develop the required hardware and software (including associated technical areas like mechanics, electronics and software), but also

  • a deep understanding of the targeted application (or what application should be targeted to find a market of substantial size with sufficient margin),
  • the knowledge of possible alternative approaches and their advantages and disadvantages,
  • the knowledge of desires and pain points of people who are supposed to use the new technology,
  • the understanding of various factors limiting the realistic market volume,
  • the capability to judge growth potentials after initial market penetration, and
  • the ability to work out suitable instruments to identify and convince the key players in the field.

Note that it may be necessary to first identify some application and market which is suitable for initial entry and establishment of the technology, while a substantial growth potential can later on only be reached by entering other applications – which however may be too difficult to enter straightaway, because initially one lacks the credibility and the resources.

The initial impetus for developing a new photonic application often comes from scientific researchers or engineers who realize that their technology can be used in new areas, and are able to develop the technology, but often do not only lack the capital for the necessary investments but also some of the competencies described above. Therefore, an important element for making progress are institutions which can bring together suitable people such that the required combination of competencies and resources is achieved. For example, there are non-profit technology commercialization centers, which are subsidized by governments with the goal of supporting new technological developments with a substantial economic potential. Also, there are specialized private companies offering services for technology development, including market studies, the development of strategies for introducing new applications, and the identification of suitable instruments of product marketing.

Similar kinds of support can also be useful where the development of new technology is originally driven by demand in certain application areas. While this approach may make it easier to address markets which really exist, rather than just searching for problem which is suitable for an already developed solution, there is again the requirement of a combination of special competencies.

Questions and Comments from Users

2021-02-07

How about photonics used in chips – does that fall under optoelectronics?

Answer from the author:

It depends. Sometimes, photonics on photonic integrated circuits may not involve electrical functions (like photodetectors and optical modulators), and then it is not optoelectronics.

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Bibliography

[1]Conference proceedings Photonics, edited by M. Balkanski and P. Lallemand, Gauthier-Villars, Paris (1975)”
[2]C. Roychoudhuri (ed.), Fundamentals of Photonics, course for first- and second-year college students, available on CD-ROM or online open access via http://spie.org/x17229.xml
[3]B. E. A. Saleh and M. C. Teich, Fundamentals of Photonics, John Wiley & Sons, Inc., New York (1991)
[4]Day of Photonics, http://day-of-photonics.org/

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See also: quantum photonics, laser physics, optoelectronics, quantum electronics, optics, silicon photonics, photonic integrated circuits
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