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Fiber-coupled acousto-optic modulators: how a clever little package continues to shape the future


For many OEMs involved in material processing within manufacturing, fiber and fiber-coupled lasers are at the heart of the value they deliver to their end clients across different application areas.

Controlling the output from these fiber optic lasers – the timing, intensity, and temporal shape of the beam — is critical. So, too, is the ability to do this reliably, efficiently, cost-effectively, and in a way that is tailored to the requirements of the specific design and application in question. In many cases, the key component enabling this control is a fiber-coupled acousto-optic modulator (FCAOM).

Back in 2009, G&H combined its micro-optical packaging capabilities and acousto-optic expertise to create a groundbreaking device for the fiber laser industry. The resulting Fiber-Q® brought the flexibility and reliability of acousto-optics to the fiber optic industry for the first time, in the form of a compact, robust, low loss device that could be easily integrated into all-fiber laser architecture without compromising on the key benefits offered by fiber-based systems. This versatile package set the bar for fiber-couple acousto-optic modulators.

Today, many laser applications have come to rely on Fiber-Q for its high performance and durability, while its versatility has seen the product adopted for a wide range of applications. But Fiber-Q is not standing still. The G&H team are continuously evolving the device for new and emerging technologies.

G&H Fiber-QG&H Fiber-Q©️ G&H

Award-winning design delivers benefits

Firstly, any instability or failure in a FCAOM costs time and money, as it necessitates rework, and it can also negatively impact relationships with end clients. Fiber-Q solutions are engineered to overcome these risks on all fronts. Subjected to rigorous, vertically integrated, in-house quality control – from crystalline material selection and orientation, to cutting, polishing, and anti-reflection coating, through to fiber coupling – the high-reliability design (winner of both the Queen’s Award for Enterprise and the Institute of Physics Award) is translated seamlessly into a high-reliability final product.

Secondly, performance is critical to answering customers’ needs, so the Fiber-Q range is optimized to perform better over longer periods. It combines low insertion loss with high extinction ratio (efficiency of conversion from electrical to optical power), and low power consumption.

Robustness is also a key consideration for many customers – particularly in harsh environments like Aerospace and Defense (A&D) and space applications. Fiber-Q solutions are sealed to IP54 standard as a minimum, to keep dust and particles out, and are also available in hermetically sealed, gold-coated, and ruggedized variants.

Additionally, the physical size and footprint of components like these can often pose a problem for integration into complex fiber and OEM systems. Fiber-Q addresses this through compact and low-profile packaging that creates a product little larger than a matchbox.

All in all, the Fiber-Q range has been developed to deliver outstanding performance and dependability whilst offering flexibility of design across acoustic frequency ranges of up to 330 MHz and optical wavelengths ranging from visible to infrared (400nm–2200 nm).

Nonetheless, the reality is that applications, designs, and environments are often not standard, and require tailored solutions – so how does Fiber-Q respond to this challenge?

Flexing with the feedback

G&H is committed to working with customers to develop Fiber-Q to make it suitable for the specific customer application in which it is being used. This adaptability ensures lower design redundancy (the inclusion of all the right elements and nothing that isn’t needed), which in turn delivers operational and economic efficiencies that the use of a “one size fits all”, off-the-shelf component simply couldn’t match.

It is this process of achieving customization for both custom projects and volume manufacture – whilst still subjecting the outputs to the same rigorous failure rate analysis and quality control as all G&H products – that has seen variants of Fiber-Q deployed in diverse markets and applications throughout the world.

So, what do these markets, applications, and emerging opportunities look like?

Man making G&H Fiber-Q©️ Private

Fiber-Q in the real world – Where it’s used?

Fiber-Q has established itself as the go-to FCAOM solution across disciplines and with many global customers.

In sensing, Fiber-Q is widely used in lidar (light detection and ranging) equipment. Fiber-Q’s ability to modulate quickly with a very high extinction ratio makes it ideal for creating the short pulses of light that lidar systems emit to reflect from, detect, and locate objects or perturbations in the sensing medium. Specific applications include wind sensing, fiber sensing (for security and protecting pipelines and other linear assets), 3D imaging, and pollution detection and monitoring.

In industrial laser applications, Fiber-Q’s reliability and performance are key to the successful execution of many machining tasks carried out by ultrafast lasers, such as cutting, marking, welding, scribing etc.

In space, Fiber-Q is playing a part in overcoming the challenges of space communications and exploration. Its ability to cope with the toughest conditions means it can be integrated into space technologies, from satellites to spacecraft. On earth, Fiber-Q is also used in pioneering telescope technology including some of the world’s most innovative array projects.

In academic and emerging markets, Fiber-Q has been deployed in the emerging field of quantum technology, a game-changing and heavily government-funded discipline that, in the near future, will impact everything from sensing and timing (for gravimeters, GPS-free navigation, and medical imaging) to quantum key distribution for cryptography, cyber security, and secure computing and communications.

Many experiments and developments in this arena make use of the frequency-shifting property of acousto-optic and FCAOM devices, and Fiber-Q significantly simplifies the optical architecture of these experiments, so we expect its role in quantum to grow rapidly.

What’s next?

The Fiber-Q wavelength range is ever expanding, opening up new possibilities for OEM customers. G&H is a global pioneer in offering wavelengths of 400nm for the first time. Meanwhile at the other end of the scale, Fiber-Q can accommodate wavelengths as high as 2200nm. This flexibility enables Fiber-Q to continue to keep pace with advancements across a broad range of technology markets.

Plus, exciting new innovations for Fiber-Q are just around the corner. Higher specification devices with much improved extinction ratios and polarization are currently in development. Also on the horizon, an acousto-optic tuneable Fiber-Q and a new design to include both the driver and Fiber-Q in a single compact package for better performance and smaller build size.

What’s certain is thatbecause customization and flexibility are built into the Fiber-Q development orthodoxy – combined with more than 70 years of G&H engineering expertise, scientific knowledge, and world-class Research & Development (R&D) capabilities – Fiber-Q looks set to remain at the forefront of innovation in the fiber laser industry.

Find out more about the Fiber-Q® range