Tough enough for space, stable enough for quantum: Fiber-Q®

“Fiber-coupled acousto-optic modulators” (FCAOM) is perhaps not a phrase that rolls naturally off the tongue. Yet this slightly awkward descriptor belies an elegant and robust solution for directly controlling the timing, intensity, and temporal shape of the output from fiber lasers – which enables them to be used in some of the most demanding applications in the world, including quantum and space.

At G&H, our take on FCAOM is Fiber-Q®, a product developed in 2008 that draws on our extensive expertise in acousto-optic technology, fiber optics and photonic packaging.

Winner of both the Queen’s Award for Enterprise (Innovation) and the Institute of Physics (IOP) Award for Innovation, this range of matchbox-sized solutions, in wavelengths from 397 nm to 2000 nm, is a powerhouse of potential for organisations seeking to respond to the opportunities of a rapidly growing quantum research trend, as well as for OEMs specializing in components and systems for the ever-expanding space applications market.

To put this into perspective, quantum technology is currently the subject of massive investment worldwide, across public and private sectors, with many Governments (the US, UK, China, Japan and Germany amongst them) running large, multi-year programs at funding levels that exceed US$1 billion.

Equally, space is growing exponentially in importance as an application area for optics and photonics, across disciplines including remote sensing, spectroscopy, lidar, space communications, and many others, with Morgan Stanley predicting that the revenue generated by the global space industry may increase to more than US$1 trillion by 2030.

As these applications become more exacting and more demanding, however, precision, stability, accuracy and reliability all become more critical – and this is where Fiber-Q® addresses some fundamental challenges.

The ultimate control of light

Quantum technology depends on the ability to manipulate and control tiny quantum objects, such as photons, atoms and electrons, using a laser light source, and this requires extraordinary levels of exactitude.

The energy projected onto these objects must be extremely stable in terms of power, but also targeted enough to ionize – in some applications, including atomic clocks – a single atom.

Quantum technology is still heavily research-focused, but there are clear potential applications for the technology in a number of practical areas.

Sensing and timing, for example, could benefit from the sensitivity of quantum systems to environmental influences to measure physical properties with more precision.

Communications could exploit quantum characteristics to more easily detect observation of, or interference with, networks, even between users over vast distances.

Computing, in turn, could use quantum principles to solve some types of problem much faster than classical computers can.

What is common between all these environments is that in such minute applications of energy there is little, if any, room for error, and this is where Fiber-Q® really comes into its own.

Unlike traditional methods of modulating fiber lasers, Fiber-Q® does not require users to control the optical beam characteristics within the modulating medium. Instead, modulation and beam shaping functions are combined within a compact and robust fiber coupled package. The hermetic package seals the optical parts in a dry and inert atmosphere ensuring stability and reliability.

Just to put some figures on this, we’re talking here about insertion loss as low as 2 dB, an extinction ratio of 50 dB, return loss of 40 dB and polarization extinction ratio of 20 dB.

Ultimately, this delivers not only higher beam quality, but also a far greater degree of control over the temporal characteristics of the output from the fiber laser (that is, its pulse rate), and a wider variety of pulse shapes (that is, the duration and complexity of each pulse).

This is the kind of performance that is critical to quantum applications – and in Fiber-Q® it comes in a package that is robust enough to be mass-manufactured reliably, delivers a defined input and output simply by matching fiber to it, and saves significant time and effort in the alignment process.

Precision and reliability in the harshest conditions

In a sense, it is somewhat artificial to distinguish between quantum and space, since the principal potential applications of quantum we mention above are each arguably vital to space activity too.

However, as an environment, space overlays significant additional challenges onto any technical component.

Extreme negative temperatures, shock, vibration, radiation, and operation in a complete vacuum are all issues that can adversely affect component reliability. At the same time, space applications, by their very nature, also tend to demand systems with a small physical footprint and low weight, and this necessarily requires the use of compact components.

Here, again, Fiber-Q® delivers. Built for reliability, the range features a ruggedized, hermetic design in a compact, low-profile package – no bigger than a large matchbox – ideal for ease of integration into fiber systems where an optimum SWaP (Size, Weight and Power) ratio is critical.

G&H components have been used in many national space agency missions and programs, including Mars Perseverance Rover 2020, Hayabusa 2, ExoMars TGO, and ExoMars Rover, so Fiber-Q® is already part of a much wider space success story that has seen G&H research, develop, test and certify many of its solutions for space use.

Fiber-Q®: a success story down on earth too

Theopportunities of quantum and the ever-developing possibilities of space are of course hugely exciting for our Fiber-Q® range, and with our research heritage and in-house expertise, we are in a strong position to continue developing forward-thinking solutions to meet future challenges – but not just in space and quantum.

Our visible-spectrum Fiber-Q® variants, for example, enable more compact, effective, all-fiber instrument designs for life-saving biomedical applications such as microscopy and flow cytometry.

In short, whether it’s quantum, space, biomedical, or any other application, Fiber-Q® is just another platform for us at G&H to do what we do best: changing the world with photonics.