Photonics is a field that has seen incredibly rapid developments in the last 25 years. Modern photonics is said to have begun in the 1960s with the development of the first lasers1 and has the potential to become a £50 billion industry in the UK alone.2
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Many of those advances have been supported with developments in the materials used for photonic devices, including the high-precision engineering methods required to create them. This includes new ways of processing silicon, which is still one of the most widely used materials for the creation of fiber optic cables. More recently, 2D materials have become increasingly popular in nanophotonics and new materials are routinely being developed for use in photovoltaics.
Optical Fibers and Telecommunications Lasers
The last 20 years have seen a huge change in telecommunications, from only 7% of the world’s population having access to the internet in 2000, to over half the global population by 2022.3
For telecommunications technologies, this has led to a huge increase in the amount of data that is being transferred and a need for technologies with increasing bandwidths.
One of the biggest innovations has been developments in optical fiber technologies. There has been a dramatic shift away from existing copper wire-based technologies such as ADSL owing to the enhanced bandwidth, data transmission speeds, and fidelity that light-based data transfer offers.
The first non-experimental optical fiber link was installed in the UK by the Dorset police in 1975. Now, fiber optics make up the Fiber Optical Link Around the Globe (FLAG) which is the longest single fiber-optic network in the world and carries a significant amount of internet traffic to this day.4
Alongside development in the engineering of optical fibers and in communications protocols to prevent data loss and manage encryption, there has been significant progress in laser technologies for telecommunications. Typically, laser sources operating in the infra-red region are preferred for telecommunications applications as little light is absorbed by the fiber optics and so transmission losses are minimized.
Key developments include the creation of high-power and high-repetition-rate sources, and also the use of semiconductor technologies to allow for minimization of device footprints.5,6 This has helped increase transmission distances without the need for as many signal repeaters, as well as the possibility for integrating laser systems directly into photonic devices rather than needing separate sources.
One area where high-power lasers have made new scientific possibilities a reality is in fusion. Recently, 10 quadrillion watts of fusion power were generated for the first time at the National Ignition Facility located in the Lawrence Livermore National Lab. While this power was only generated for a fraction of a second, this amount of power is approximately 700 times the amount generated by the US electrical grid.7
The laser source required to do this is a 500 TW 0.35 µm source that is split into multiple beamlines to simultaneously irradiate a fuel sample. The collapse of the fuel is then designed to trigger the highly energetic fusion processes.8 The National Ignition Facility is not the only laser source generating such intense beams, with several petawatt and exawatt sources available worldwide.9
While chirped pulse amplification made it possible to generate instantaneous powers from the megawatt to gigawatt range, achieving above this has required the refinement of optical parametric chirped pulse amplification (OPCPA) as a technology to provide both high peak and average pulse energies.
Many fusion laser sources rely on very short (femtosecond) pulse generation as a way of achieving the incredibly high peak powers due to the shorter temporal duration of the pulses needed to trigger the fusion processes.
High-power laser developments have also led to new manufacturing possibilities, with such laser systems being used for welding and cutting applications. Even for less extreme environments such as the use of lasers to excise tumors or for eye surgery, high-power femtosecond lasers are often the instrument of choice.
CO2 lasers were one of the most popular lasers historically for such applications but now there are an increasing number of solid-state laser systems that can be diode-pumped to generate sufficient power. Fiber lasers can do this in a relatively energy-efficient fashion as well as generate diffraction-limited output spot sizes.
Next-Generation Camera Technology
As advanced laser technology such as OPCPA systems has made it possible to achieve much higher repetition rates at reasonable pulse energies – with many systems capable of generating 100 kHz or above – detection technologies have also undergone significant advances.10
Particularly for many research applications, it can be very beneficial to use shot-to-shot detection schemes. This means that the detector needs to work at the same repetition rate as the pulsed laser source. The advantage of such schemes, particularly for noisy laser sources, is that it is possible to correlate signal fluctuations with changes in the source. This makes it possible to correct some amount of laser-induced noise using suitable photon diagnostics and improve the signal-to-noise ratio of the overall experiment.
However, particularly for multipixel array detectors, reading out all the information from a camera chip between lasers shots is very challenging due to the amount of data that needs to be transferred.
CMOS-based camera sensors have become particularly prevalent for such applications due to their chip architecture lending itself to much higher read-out rates.11 Improvements in detector sensitivity and noise have also made CMOS technologies comparable in performance to CCDs. Now it is possible to achieve over 10 kHz readout speeds for even relatively complex multidimensional imaging schemes.11
Optical Imaging and Sensing
Photonics-based sensing has become one of the biggest growth areas in photonics. Photonic sensors can be used for a vast array of applications, from chemical or biological detection of bacteria and viruses to LIDAR systems for automated vehicles. Recent developments have included the use of atomic systems as quantum sensors that could become part of quantum metrology systems.12
In comparison to traditional camera-based optical imaging and sensing systems, quantum sensors could offer a new realm of precision in the accuracy of measurements. Using squeezed states, it is possible to achieve ultra-high precision measurements with a resolution that is beyond the wavelength limit.
However, while quantum sensors are still challenging to engineer as the systems often must be well isolated from external perturbations such as vibrations, advances in more conventional optical sensing technologies, such as optical fibers have also led to huge improvements in accuracy.
Optical fibers can not just be used to transmit information but as part of distributed sensing networks that can be used even in very challenging environments and remote locations.13 Here, techniques such as reflectometry are used to measure the disturbances to a pulse sent down to the length of the fiber that can be affected by external perturbations. The engineering of such fibers makes it possible to create sensors that are kilometers in length and are particularly well-suited for geological monitoring studies.
New technologies and methodologies have also had a great impact on optical imaging. From the use of nanoparticles to enhance signals in Raman microscopy experiments14, to the wealth of super-resolution microscopy approaches15
Liquid Crystal and Organic Electronic Displays
The first liquid crystal displays were developed in the 1960s and become commonplace on many electronic objects but recent developments in thin-film transistors in conjunction with liquid crystal displays have helped this technology achieve significantly greater imager qualities. There has been a recent shift away from using silicon as the material for transistors for these applications to other new semiconducting materials as a way to further enhance device performance.16
Organic electronics have proved a highly active area of research with new materials in constant development as a way of offering new types of flexible screens as well as low-cost devices that can be printed on plastic.17 Advances in deposition techniques to create the layers of organic electronics have been instrumental alongside the creation of chemical targets that have the desired electronic properties and long lifetimes to ensure good device longevity.
While liquid crystal displays still account for most of the display market, the desire for wearable technologies will likely see further development of organic electronic displays.
The ability to turn organic electronics into inks for processing offers many advantages over traditional silicon electronics, which require very high temperatures for processing. It has made it possible to achieve designs that could not be done with traditional silicon.
Overall, the last 25 years have been an incredibly exciting time for photonics. Many of the developments in hardware have also been accompanied by a similar improvement in method automation, enabled by similar developments in computer processing capability and machine learning methods. Decreasing manufacturing costs and new materials will also help make many of these new technologies more commonplace.
References and Further Reading
- Kryuchkyan, G. Y., Gurzadyan, G. G., & Papoyan, A. V. (2010). Modern optics and photonics: Atoms and structured media. World Scientific.
- Optics News (2021) UK Photonics Vision, https://optics.org/news/12/11/3,
- Hillyer, M. (2021) How has technology changed? https://www.weforum.org/agenda/2020/11/heres-how-technology-has-changed-and-changed-us-over-the-past-20-years/
- Conway, E. (2019). Optical Fiber Communications Principles and Practice. Scientific e-Resources.
- Wang, Z., Zhang, B., Liu, J., Song, Y., & Zhang, H. (2020). Recent developments in mid-infrared fiber lasers: Status and challenges. Optics and Laser Technology, 132, 106497. https://doi.org/10.1016/j.optlastec.2020.106497
- Zhang, G., Takiguchi, M., Tateno, K., & Tawara, T. (2019). Telecom-band lasing in single InP / InAs heterostructure nanowires at room temperature. Science Advances, 5, eaat8896. https://doi.org/10.1126/sciadv.aat8896
- Tollefson, J. (2021). Controversial us facility achieves laser-fusion record. Nature, 597, 163. https://doi.org/10.1038/d41586-021-02338-4
- Hogan, W. (2021), The National Ignition Facility, https://www-pub.iaea.org/mtcd/publications/pdf/csp_008c/pdf/if_3.pdf
- Danson, C., Haefner, C., Bromage, J., Butcher, T., Chanteloup, J., Chowdhury, E., Galvanauskas, A., Gizzi, L., Hein, J., Hillier, D., Danson, C., Haefner, C., Bromage, J., Butcher, T., Chanteloup, J., Danson, C. N., Haefner, C., Bromage, J., & Butcher, T. (2020). Petawatt and exawatt class lasers worldwide. High Power Laser Science and Engineering, 7, 54. https://doi.org/10.1017/hpl.2019.36
- Puppin, M., Deng, Y., Prochnow, O., Ahrens, J., Morgner, U., Krenz, M., Wolf, M., & Ernstorfer, R. (2015). 500 kHz OPCPA delivering tunable sub-20 fs pulses with 15 W average power based on an all- ytterbium laser. Optics Express, 23(2), 1491–1497. https://doi.org/10.1364/OE.23.001491
- Brübach, V. W. J., & Dreizler, R. L. G. A. (2011). Pixel-based characterisation of CMOS high-speed camera systems. Applied Physics B: Lasers and Optics, 103, 421–433. https://doi.org/10.1007/s00340-011-4443-1
- Pirandola, S., Bardhan, B. R., Gehring, T., Weedbrook, C., & Lloyd, S. (2018). Advances in photonic quantum sensing. Nature Photonics, 12https://doi.org/10.1038/s41566-018-0301-6
- Mescia, L., Prudenzano, F., Elettrica, I., & Via, B. (2014). Advances on Optical Fiber Sensors. Fibers, 2, 1–23. https://doi.org/10.3390/fib2010001
- Schlücker, S. (2009). SERS Microscopy : Nanoparticle Probes and Biomedical Applications. ChemPhysChem, 10, 1344–1354. https://doi.org/10.1002/cphc.200900119
- Coltharp, C., & Xiao, J. (2012). Superresolution microscopy for microbiology. Cellular Microbiology, 14, 1808–1818. https://doi.org/10.1111/cmi.12024
- Paterson, A. F., & Anthopoulos, T. D. (2018). Enabling thin film transistor technologies and the device metrics that matter. Nature Communications, 9, 5264. https://doi.org/10.1038/s41467-018-07424-2
- Forrest, S. R. (2004). The path to ubiquitous and low-cost organic electronic appliances on plastic. Nature, 428, 911–918. https://doi.org/10.1038/nature02498
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