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S+D 2016: Fiber lasers and quantum photonics show great promise

28 Sep 2016

SPIE’s Edinburgh Defense & Security meet hears inspirational plenaries from Payne and Knight.

by Matthew Peach in Edinburgh

This week’s busy Security + Defence/Remote Sensing conference in Edinburgh, Scotland, organized by SPIE, heard plenary sessions from luminaries in the fields of fiber lasers and quantum technologies.

First up was Sir David Payne, Professor of Photonics and Director of the Optoelectronics Research Centre and the Zepler Institute at the University of Southampton, where he has worked for more than 50 years. Prof. Payne’s work in fiber fabrication in the 1970s resulted in most of the special fibers used today, including his revolutionary erbium-doped fibre amplifier and kilowatt-class fibre lasers used increasingly in manufacturing and defense applications.

After being introduced by symposium chair and SPIE Fellow David Titterton of the UK Defence Academy, Prof. Payne took the delegates on a whirlwind tour through the past four decades of fiber lasers and explained that this technology has much more to offer defense and sensing applications.

“There are several disruptive photonic technologies emerging that could change sensing, security and defense, which as ever, are materials-based, “ he said. “Now low-loss fibers can be made from almost any material – we have even demonstrated the lasing effect in fibers we have made from cookware glass to illustrate the potential.”

He also described recent advances in bismuth- and holmium-doped fibers and the promising potential of two-dimensional materials such as molybdenum disulfide. He said, “Really, this is an exciting time for fiber-based mid-IR sensing.”

'Megawatt potential'

Prof. Payne emphasized that the multiple kilowatt outputs already achieved and the eventual megawatt potential of fiber lasers have “caught the imagination for applications requiring beam combination up to a 100kW in the near term, or multi megawatts in the future.” But he also stressed that the current optimal fiber laser performance, efficiency and lifetime remained at about one kilowatt and that there was plenty more research and developmental work to undertake.

He added, “Their near-perfect beam quality, stability and versatility, coupled with the low cost of the gain medium, make these kilowatt fiber sources ideal candidates for coherently combining perhaps up to a 1000 individual fiber amplifier beams. With a few kilowatts being the most practical and reliable sweet spot for robust individual fibre laser emitters, we need to consider beam combination for power scaling, either spatial, by wavelength or coherently.”

He also described the progress of research and development towards higher power, single-frequency lasers as well as the prospects for beam combination to overcome the pulse energy limitations that result from the small active volume of the fibre core. “Together with chirped pulse amplification, several gigawatts of peak power have already been reported,” he said.

Prof. Payne reviewed the prospects for 2µm to 5µm eye-safe fiber lasers in directed energy sources [laser weapons] or “DIRCOM” counter measures. Considering their suitability for security and defense applications – and paraphrasing the famous beer commercial slogan from the 1970s – he said that the fiber laser is now reaching parts that other lasers cannot reach. “Today’s frontiers of fiber laser research are new wavelengths in the mid-IR, the development of shorter pulse to femto- and picosecond durations and the potential of massive parallelism,” he said.

Quantum of opportunity

”Quantum Technology for a Networked World” was the title of the plenary presented later by Professor Sir Peter Knight, of the Blackett Laboratory, at Imperial College, London.

He said, “The 21st century has seen the emergence of a networked world, connected by global fiber-optic communications and mobile phones, geo-location provided through GPS, and all this has changed our lives more dramatically than at any time since the industrial revolution.”

Quantum-enabled technology based on photonics is at the heart of this change. Prof Knight continued: “The quantum world allows information to be encoded and manipulated in ways quite different from classical physics. The two main pillars of quantum technology – parallelism and entanglement – are enabling us to undertake information processing tasks peculiar to the quantum world.”

This has significant implications for security and defense applications: secure encryption, quantum teleportation and algorithmic computational acceleration. New developments in quantum technology, and in particular miniature atomic clocks have the potential for even more dramatic applications. Some of these include communications systems immune to GPS jamming, as well as quantum sensors for medical applications, more sensitive magnetometry, gyros, and geophysical surveying [as have been described in numerous other S+D presentations in Edinburgh, this week].

Prof Knight said, “Quantum physics has the potential to crack industry encryption standards through the development of quantum computers, although this is a long-term ambition rather than a near-term realization. Quantum physics also has a role in generating secure “one-time pads” (for uncrackable cryptography) and provable security systems.

During his talk, he also described the quantum phenomena already being exploited and planned for further investigation by the UK’s National Quantum Technology Initiative, announced in the past year, which is investing £350 million over a five-year duration in this area.

Within the UK Defence Community, Prof Knight said, quantum technologies considered as a key resource for providing innovative capabilities included the following:

  • Sensing – quantum technology opens up new sensing domains : improved optical and gravitational imaging.
  • Navigation – the Quantum Navigator using atomic inteferometers for accelerometers and rotation sensors may offer a more resilient navigation solution than GPS.
  • Precision Timing – a quantum approach removes current reliance on susceptible GPS solutions and like GPS a future quantum-based precision timing solution could also include accurate Navigation functionality to support operation in GPS denied environments.
  • Computing – Quantum computers may easily solve problems that today’s computers struggle with: breaking difficult cryptographic ciphers and providing new methods for materials simulation and optimisation.

He concluded by predicting which quantum technologies would be deployed in which applications in the near and medium terms: quantum clocks within five years; communications, including hand-held QKD systems, and quantum sensors for metrology, navigation and gravity sensing within the next decade; and quantum computing and even “quantum materials” in 15 years or so.

About the Author

Matthew Peach is a contributing editor to optics.org.

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