Posted to News on 4th Jul 2025, 12:00
Characterising advanced lasers for quantum computing
Yokogawa optical spectrum analyser are proving 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 (xtagstartz1 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
