About Modulight
The development and manufacturing of laser systems for biomedical and life sciences applications requires extremely high levels of precision, control, and stability. In applications such as photodynamic therapy, photoimmunotherapy, fluorescence imaging, and biomedical illumination, the laser output is not judged only by power, but also by spectral performance. The wavelength must be right, the spectral profile must be understood, and weak optical content close to the main signal must be visible clearly enough to support confident engineering decisions.
Modulight is a Finnish laser manufacturer serving life sciences and biomedical markets, alongside other high value‑add applications. Its technologies support demanding uses such as cancer treatments and ophthalmology. The company was founded in 2000 and is today a publicly listed international business.
As a vertically integrated laser manufacturer, Modulight’s in-house capabilities span epitaxial growth, chip fabrication, and laser systems assembly. Its laser portfolio covers wavelengths from ultraviolet (UV) to beyond 3,000 nm (MIR), enabling a broad range of applications in oncology, ophthalmology, fluorescence endoscopy, flow cytometry, and biomedical research. Modulight has leveraged their semiconductor laser know-how into many laser technologies, including multimode laser diodes, single-mode and single-frequency lasers, VCSELs and VECSELs, among others.
Modulight is a trusted supplier and exclusive laser partner to leading pharmaceutical companies, cancer centres and Fortune 500 customers . With the entire production chain of the lasers in their hands and also medical research centre, 25+ years of active involvement in the field, and a team with significant semiconductor laser experience, it is no surprise that they have been rapidly growing.
The Challenge
Background
Many of the most demanding biomedical laser applications depend on a precise spectral match between the laser source and a target molecule. Photodynamic therapy relies on lasers that emit at wavelengths matching the photosensitizer’s absorption, ensuring that the photochemical reaction remains confined to the target tissue. Modulight applies this same principle in clinical use cases such as age‑related macular degeneration, and integrates it into its laser platforms for PDT, PIT, and fluorescence imaging.
Photosensitizers, fluorophores, and other molecules absorb only within a narrow wavelength band. Being off by even a few nanometers can reduce efficacy. For Modulight, the challenge goes beyond confirming just the center wavelength. The company also needs to control the spectral width (linewidth) to ensure the emission is narrow and avoid off-target excitation, maintain stability over time and temperature to prevent peak drift, and minimize side modes or secondary peaks that could introduce unwanted wavelengths. Different applications impose different optical requirements, so the engineering teams evaluate multiple parameters when characterizing laser emission. Depending on the use case, this can include the examining spectral tails, comparing filter transmission against the actual laser spectrum, or detecting weak spectral features adjacent to much stronger ones.
The challenge
This is particularly important in fluorescence-related systems. A strong excitation line can sit very close to a much weaker optical feature, and both need to be seen clearly. If noise obscures the low-level signal, or if the analyser cannot provide enough dynamic range, the engineer loses visibility into behaviour that may matter in the final application.
The challenge is made harder by the wavelength range in which Modulight works. According to Dr. Lasse Orsila, Optical Engineer at Modulight and medical doctor, many relevant biomedical and life sciences applications are in the visible range, where the choice of suitable optical spectrum analysers is narrower than in telecom or near-infrared bands. Modulight therefore requires a spectrum analyzer platform that could combine wavelength accuracy, strong sensitivity, wide dynamic range, and practical usability across a wide span of laser development tasks, while also covering the broad wavelength range offered by Yokogawa’s analyzers.
The Solution
Application requirements
Working across a broad optical range and for a wide variety of clinical and biomedical applications, optical characterization is a central part of development, validation, and production. Modulight needed an optical measurement platform that could serve both R&D and production-facing work. In applications such as fluorescence imaging, fluorescence endoscopy, photoimmunotherapy (PIT), and ophthalmic treatment and diagnostics, engineers need more than a strong output signal. They need precise wavelength control, stable output power, low noise, and enough spectral visibility to understand exactly how the laser is behaving across the full emission profile.
For Modulight’s teams, the essential measurement tasks include accurate centre wavelength verification, linewidth evaluation, observation of low-level spectral content, and comparison of traces under different conditions. In filter measurements, for example, the engineers want to compare the actual signal from their own laser source before and after the filter, rather than rely only on generic spectrophotometer data. In fluorescence and biomedical illumination, engineers need to see a weak optical response beside a dominant laser line.
This places particular importance on sensitivity, dynamic range, and clean spectral visibility. If low-level optical content is masked by noise, engineers lose insight into behaviour that may matter in the final application.
Dr. Lasse Orsila shares an insight into the evaluation of the lasers: “Obviously wavelength is an important parameter. Other parameters are also very important depending on use-case, such as dynamic range when measuring filter properties. Certain metrics like side-mode suppression ratio allow engineers to quickly determine pass/fail for single-mode lasers, without requiring additional measurement equipment or manual calculations.”
Measurement solution
To achieve this level of insight, Modulight relies on high-performance optical spectrum analysis. Engineers use multiple Yokogawa OSAs covering different wavelength ranges to support work in the production facility as well as in R&D laser laboratories, where chip- and bar-level testing is also performed. With multiple laser models spanning the ultraviolet (UV) to mid-infrared (MIR), Modulight faces a challenge in finding measurement solutions that are reliable, comprehensive, and capable of handling the full spectral range.
“What I value in the Yokogawa optical spectrum analyzers is their reliability and precision. They are also very easy to use”, explains Dr. Orsila. “The availability of OSAs in the visible range is much more limited than in the telecom or near-infrared ranges. Yokogawa can cover nearly all the wavelength ranges we work with, and performance in the visible range is particularly important to us.”
The world`s most trusted Yokogawa OSA AQ6370E Optical Spectrum Analyzer 600 - 1700 nm
High-performance Yokogawa OSA AQ6373 optimized for visible spectrum measurements
Modulight’s workflow is therefore built around Yokogawa OSA tools for visible-light characterization, trace comparison, filter assessment, and low-level spectral analysis. The AQ6373E supports visible-light spectra characterisation where wavelength placement and spectral shape are especially important, while the AQ6370E units provide broader flexibility for trace comparison, filter assessment, low-level signal visibility, and detailed laser-source analysis. Their precision, reliability and extreme lifespan have garnered a lot of trust at Modulight. Apart from technical measurement benefits, one example that Dr. Orsila brought up is the ability of Yokogawa devices easily compare traces with other traces that have been recorded on the device, with built-in analysis tools.
Results
AQ6373 and AQ6370: Spectral clarity and long-term reliability strengthen Modulight laser development
The use of Yokogawa’s AQ6373E and AQ6370E optical spectrum analyzers has given Modulight a dependable measurement platform for characterizing laser performance across visible and near-infrared (NIR) applications. With the ability to detect and characterize center wavelength, linewidth, spectral tails, signal strength, low-level spectral content, and SMSR with greater clarity, Modulight’s engineers can build a more complete picture of laser behaviour during development. This is especially valuable in demanding areas such as the development of fluorescence-based systems, photoimmunotherapy, and ophthalmic laser applications, where spectral precision and clean optical output are critical.
“The high signal-to-noise ratio, wide dynamic range, and strong sensitivity in the visible range allows us to obtain reliable measurements – even at very low optical signal levels.”
Lasse Orsila, Optical Engineer, Modulight and medical doctor
Beyond the immediate measurement capability, the Yokogawa platform has helped make optical characterization more practical day to day. Clearer signals, strong sensitivity, and the ability to record, compare, and analyze traces within the instrument workflow give engineers a faster and more confident way to evaluate devices and the performance of optical filters. With Yokogawa’s instruments, engineers can perform measurements more efficiently and compare lasers across types and wavelengths with ease.
Reliability is also a major part of the result. For Modulight, trust in a measurement platform is built over years of use, not just a single specification sheet. The long service life of Yokogawa optical equipment (previously known under Ando name), combined with excellent usability, support, and consistent performance, has helped establish the analyzers as a trusted part of the company’s workflow.
As a result, Modulight can validate laser behaviour with greater clarity and consistency in the quality of its spectral data. By combining visible light range capability, deeper near-infrared light analysis, and a practical engineering workflow, Yokogawa’s analyzers help ensure that demanding medical and photonic laser technologies can be validated with the precision, repeatability, and clarity they require.
