About Vexlum
Quantum computing holds enormous promise for extending the potential of digital technology far beyond the capabilities of today’s classical computers.
The operation of quantum computers calls for the use of specialized lasers which can maintain emission at a precise wavelength in the visible or near infrared (NIR) spectrums. In trapped ion quantum computers, the lasers are used to control the behaviour of ions trapped in magnetic fields. And in a quantum computer’s supercooled optical lattice, lasers control individual atoms held in the lattice.
Such lasers are challenging, becoming more complex to design and manufacture: Vexlum is one of few companies worldwide which have the facilities and know-how to build lasers for use in quantum computers, as well as in other specialist applications including medical equipment and semiconductor fabrication.
Vexlum, based in Tampere, Finland at the city’s Optoelectronics Research Centre, is a spin-off from Tampere University. Its advanced laser technology has also built on research performed in collaboration with the US National Institute of Standards and Technology (NIST) in Boulder, Colorado.
Showing impressive mastery of every aspect of the technology of Vertical External-Cavity Surface-Emitting Lasers (VECSELs), Vexlum is a vertically integrated manufacturer of lasers: it grows the basic semiconductor materials for the production of raw wafers, operates a clean room and fabricates the emitter chips, and assembles them into laser modules. And the requirement for characterizing its VECSELs calls for the unique measurement capability provided by Yokogawa’s optical spectrum analyzers (OSAs).
The Challenge
Background
The VECSEL lasers produced by Vexlum can fulfil a wide range of operating specifications: output power can range from very low levels up to a high of 100 W. In pulsed mode, they can operate at very high speed, producing pulses as short as 100 femtoseconds.
The critical factor for quantum applications is the ability to emit light at a single frequency with a very narrow bandwidth. To produce this precise output, Vexlum’s technology controls 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: a seed laser, an amplifier, and the main emitter. The unique advantage of the Vexlum VECSEL is its single-module design, which Vexlum promotes as a ‘three-in-one’ solution. For quantum computer manufacturers, Vexlum’s single-module design offers several benefits: the single VECSEL is smaller and simpler than competing solutions. In addition, the VECSEL is proven to produce a higher optical power output than either an edge-emitting laser or a vertical-cavity surface-emitting laser (VCSEL), and emits over a very wide wavelength range, from visible wavelengths far into the NIR spectrum at up to 2100 nm.
The challenge
Quantum applications require light emission at a precise, narrowband wavelength. If the VECSEL is designed to reliably emit light at the specified wavelength required by a quantum application, it needs to be characterized very accurately.
But different quantum applications operate at different wavelengths: any of these wavelength requirements can be met by the Vexlum lasers, because they have such a wide wavelength range, from visible light up to 2100 nm.
What Vexlum therefore needs is an OSA which combines two capabilities:
◼︎Extremely accurate wavelength measurements, enabling it to assure the test engineer of conformance to a quantum application’s tight wavelength specification
◼A broad wavelength range from visible light up to 1700 nm
This requirement can be met by a Yokogawa optical spectrum analyzer (OSA). Drawing on more than 40 years of experience in the optical test and measurement market, Yokogawa a broad OSA product range and offers industry-leading performance. This means that it can provide the OSA with the best match for Vexlum’s requirements.
The Solution
Application requirements
Vexlum uses an OSA to develop and characterize its VECSEL lasers used in quantum computing applications. In quantum applications, the laser emission’s wavelength must be precisely controlled over a bandwidth of less than 1 nm.
To meet this requirement, Vexlum requires an OSA which can characterize its VECSEL product with <1 nm precision and minimize measurement uncertainty.
To avoid the need to maintain multiple test systems, Vexlum also requires its OSA to provide this level of precision over a wide wavelength range from the visible spectrum up to 1700 nm.
Measurement solution
The solution to cover Vexlums challenging measurement requirements lays within Yokogawa’s AQ6370E OSA which offers over a wavelength range of 600 nm to 1700 nm. Wavelength measurement accuracy is typically ±0.015 nm. Resolution is 0.02 nm.
For detailed analysis of VECSEL emissions, the AQ6370E provides a high-resolution HCDR (High Close-in Dynamic Range) mode. This is a feature for single longitudinal-mode laser measurements: it makes the spectrum around the peak sharper, and provides a clearer visual representation of the side modes than is possible in standard mode.
Besides these impressive specifications, the AQ6370E offers various features which make it easy to use, including a large touchscreen and the intuitive layout of the function keys.
Yokogawa’s AQ6370E OSA which offers over a wavelength range of 600 nm to 1700 nm
Results
AQ6370E: precise characterization of lasers for quantum applications
Vexlum has used Yokogawa instruments throughout its development, from the earliest days as a research unit of Tampere University. Today, the company’s production operations are ramping up to volume, and the company employs around 25 people, mostly in engineering functions.
According to Jussi-Pekka Penttinen, CEO, CTO and co-founder of Vexlum, Yokogawa instruments, and the AQ6370E in particular, are a perfect fit for the research, development and production operations of a manufacturer of the most advanced laser technology.
“It is not only the performance and wavelength range of the AQ6370E OSA which meet our requirements, we also really like its usability, and the scope that it gives to automate some of the test operations, to enable us to maximize our productivity in the laboratory and in the factory. We were not able to verify the performance of our VESCEL lasers without the AQ6370E — it has been essential for precise characterization throughout both R&D and production.”
Jussi-Pekka Penttinen, CEO, CTO and co-founder of Vexlum
For more information on the AQ6370E Optical Spectrum Analyzer, visit our website.
AQ6370E Optical Spectrum Analyzer
The AQ6370E is an upgraded version of the popular AQ6370D. This new model is supplied with features which enhance performance and improve usability. The AQ6370E can be used to characterize a wide range of components, including lasers for optical communications, optical transceivers, and optical amplifiers. The instrument is available in Standard and High Performance versions. The High Performance model provides even higher wavelength accuracy and dynamic range.
The benefits of the AQ6370E include:
Performance
– excellent optical wavelength resolution, accuracy and close-in dynamic range specifications allow optical signals even in narrow bandwidth to be clearly separated and accurately measured.
Productivity
– smart technology and functionality such as an intuitive touchscreen, automated wavelength calibration, optimized sweep speed and dedicated application set-up menus allow users to operate the OSA efficiently.
Expertise
– for more than 40 years, Yokogawa’s development and product specialist teams have been listening to the needs of OSA users, refining the OSA product range to provide them with innovative and effective measurement tools.
