Vexlum’s innovative lasers turn promise of quantum computing into reality

Yokogawa Test&Measurement Corporation
Amersfoort, The Netherlands – 3, July 2025

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Yokogawa optical spectrum analyser proves essential to the characterisation of advanced lasers for quantum computing applications at Vexlum

The promise of quantum computing could extend the potential of digital technology far beyond the capabilities of today’s conventional computers. However, ensuring that quantum computing fulfil its potential requires the deployment of special lasers able to keep emissions at an accurate wavelength in the visible or near-infrared (NIR) spectrums. With such lasers becoming increasingly complex to design and manufacture, the need for precise measurements over a wide wavelength range is of paramount importance.

University spin-out Vexlum, based in Tampere, Finland, is one of very few companies worldwide with the facilities, technology and expertise to manufacture Vertical External-Cavity Surface-Emitting Lasers (VECSELs) for quantum computers. The vital factor in quantum applications is the ability to emit light at a single frequency with an extremely narrow bandwidth. Generating this precise output means Vexlum’s technology must control the three main elements of a high-power laser system: the semiconductor gain, the optical pump and the external cavity.

Other laser solutions for producing high power over a narrow bandwidth require three separate components, namely a seed laser, amplifier and main emitter. In contrast, the unique advantage of the Vexlum VECSEL is its single-module concept. This ‘three-in-one’ design offers several benefits, not least its compact size and simplicity in comparison with competing products. In addition, the Vexlum VECSEL produces higher optical power output than either an edge-emitting laser or a vertical-cavity surface-emitting laser (VCSEL). 

To emit light reliably at the specified wavelength of a quantum application, the VECSEL requires precise characterisation. However, quantum applications operate at many different wavelengths. 

Vexlum overcomes these challenges by relying on Yokogawa’s optical spectrum analysers (OSAs), which combine two capabilities: ultra-precise (<1 nm) wavelength measurements that minimise uncertainty and assure the test engineer of conformance to a quantum application’s tight wavelength specification; and a wide wavelength range from visible light up to 1700 nm. By using an OSA with these attributes, Vexlum not only achieves effective characterisation of its VECSELs, but also avoids the need to maintain multiple test systems

Yokogawa’s easy-to-use AQ6370E OSA provides a wavelength range of of 600 nm to 1700 nm, supported by a wavelength measurement accuracy up to ±0.008 nm and resolution between 20 pm up to 2 nm. 

For detailed analysis of VECSEL emissions, the AQ6370E features a high-resolution HCDR (High Close-in Dynamic Range) mode that sharpens the spectrum around the peak and provides a clearer visual representation of the side modes than is possible in standard mode. 

Vexlum has been characterising VECSELs using Yokogawa instruments since its earliest days as a research unit of Tampere University. Today, the 25-employee company is ramping up its production operations to volume. At the core of this growth is Jussi-Pekka Penttinen, Vexlum’s CEO, CTO and co-founder. He knows all about the benefits of deploying the optimal OSA in the company’s research, development and manufacturing operations. 

“Put simply, we’re not able to verify the performance of VESCELs without the Yokogawa AQ6370E OSA – it’s essential for precise characterisation throughout our R&D and production,” he says. “It’s not only the performance and wavelength range of the OSA that meet our requirements, we also really like its usability. Moreover, the scope it provides to automate test operations enables us to maximise productivity in our laboratory and factory.” 

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About Yokogawa Test & Measurement

Yokogawa has been developing measurement solutions for 110 years, consistently finding new ways to give R&D teams the tools they need to gain the best insights from their measurement strategies. The company has pioneered accurate power measurement throughout its history, and is the market leader in digital power analyzers and optical spectrum analyzers. 
Yokogawa measuring instruments are renowned worldwide for their high levels of precision, quality, durability, and service support. 

Meet the precision makers at https://tmi.yokogawa.com/

About Yokogawa
Yokogawa provides advanced solutions in the areas of measurement, control, and information to customers across a broad range of industries, including energy, chemicals, materials, pharmaceuticals, and food. Yokogawa addresses customer issues regarding the optimization of production, assets, and the supply chain with the effective application of digital technologies, enabling the transition to autonomous operations.
Founded in Tokyo in 1915, Yokogawa continues to work toward a sustainable society through its 17,000+ employees in a global network of 129 companies spanning 60 countries. For more information, please visit www.yokogawa.com/

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