Quantum computing pioneer relies on Yokogawa OSA to characterize complex lasers

As many of you will have read, quantum computing holds the potential to solve complex problems that are presently beyond the capability of even today’s most powerful supercomputers.

At the center of ensuring this technology meets its promise is the development of advanced lasers that must maintain emissions at a precise wavelength in the visible or near-infrared (NIR) spectrums. But there’s a problem. These lasers are extremely complex to design and manufacture. It’s therefore essential that those attempting this task take advantage of test devices able to perform accurate wavelength measurements over a broad wavelength range.

One of very few companies worldwide with the facilities, technology and knowledge to create Vertical External-Cavity Surface-Emitting Lasers (VECSELs) for quantum computers is university spin-out Vexlum, based in Tampere, Finland. VECSELs have the ability to emit light at a single frequency with a very narrow bandwidth.

Unlike other laser solutions for this application, which need three separate components (seed laser, amplifier and main emitter), the proprietary benefit of Vexlum’s solution is its single-module design.

As well as compact dimensions and simplicity, the VECSEL generates greater optical power output than both an edge-emitting laser and a vertical-cavity surface-emitting laser (VCSEL).

Key here is the precise performance verification of the VECSEL to ensure reliable light delivery at the wavelength required by the quantum computing application. However, it’s far from straightforward as quantum applications operate at many different wavelengths. The choice of a suitably capable optical spectrum analyzer (OSA) for effective laser characterization is therefore paramount.

This point is not lost on Vexlum, which relies on a Yokogawa AQ6370E OSA and its combination of two capabilities in a single device: ultra-accurate (<1 nm) wavelength measurements that minimize uncertainty and a wide wavelength range from visible light up to 1700 nm. By using an OSA with these attributes, Vexlum test engineers gain confidence in achieving effective VECSEL characterization. What’s more, there’s no need to maintain multiple test systems.

Notably, the detailed analysis of VECSEL emissions benefits from the OSA’s high-resolution HCDR (High Close-in Dynamic Range) mode, which sharpens the spectrum surrounding the peak to deliver a clearer visual representation of the side modes than is possible in standard mode.

Vexlum has been characterizing VECSELs using Yokogawa instruments since its formation, with the 30-employee research group currently ramping up its production to volume. The company says it not only values the performance and wavelength range of the Yokogawa AQ6370E, but also its usability and potential to automate test operations.