A semi-automated manufacturing procedure for resonantly tunable quantum cascade laser modules (MOEMS-EC-QCLs) has been developed by Fraunhofer IAF. This laser technology's incredibly quick and wide spectral tunability allows for inline measuring devices and real-time spectroscopy across various industries.
The Fraunhofer IAF has developed a flexible method for efficiently combining multiple MOEMS-EC-QCL modules into a multi-core system. Image Credit: Fraunhofer Institute for Applied Solid State
The procedure drastically lowers the cost and speeds up the manufacturing of the modules. Fraunhofer IAF will demonstrate the procedure using a multi-core system example at Munich's Laser World of Photonics from June 24–27, 2025 (Hall A3, Booth 431). By multiplexing four units, the device achieves effective spectral measurement speeds of more than 1 million wave numbers per second.
Resonantly tunable quantum cascade lasers (QCLs) are high-performance laser light sources for various mid-infrared (MIR) spectroscopic applications. Because of their high brilliance, they can be employed, for instance, in the chemical and pharmaceutical sectors, medicine, or security technologies. This allows for shorter measurement periods for more accurate and effective characterization procedures. However, up until now, QCL module production has been rather costly and complicated.
As a result, the Fraunhofer Institute for Applied Solid State Physics (IAF) has created a semi-automated method that greatly streamlines the manufacturing of QCL modules using a MOEMS (micro-opto-electro-mechanical system) grating scanner in an external optical cavity (EC), increasing its affordability and industrial appeal. Fraunhofer IAF worked with the Fraunhofer Institute for Photonic Microsystems IPMS to develop the MOEMS-EC-QCL technology.
Inline Measurements in Industrial Processes
The market potential of MOEMS-EC-QCLs is enormous. The high brilliance in combination with spectral tunability due to the use of MOEMS diffraction gratings enables the further development of measurement methods based on FTIR spectroscopy and their use for inline measurement technology.
Dr. Marko Haertelt, Leader, Laser Measurement Technology Group, Fraunhofer IAF
“We have now been able to bring the technology to an industry-ready level in terms of cost and availability: on the one hand, by placing the production of MOEMS-EC-QCL modules on a semi-automated manufacturing basis; on the other hand, by using a scalable approach to couple modules with complementary spectral ranges. The latter significantly reduces the number of different modules required to cover the entire MIR range from 4 to 11 µm, thereby achieving the necessary economies of scale,” emphasized Haertelt.
Semi-Automated Production of Quantum Cascade Lasers
The primary barrier preventing MOEMS-EC-QCLs from being widely used is their high production costs: Until recently, the modules could only be manually assembled since they needed to be actively adjusted. The developed procedure automates the assembly of MOEMS-EC-QCLs in critical sections using a pick-and-place system, thereby lowering manufacturing costs.
Fraunhofer IAF has also created a scalable and adaptable technique for effectively integrating several laser sources into a multi-core system. The spectral width of a single QCL module is constrained. By integrating modules with additional spectral ranges, application-specific multi-core systems can be set up to attain effective spectral measurement speeds of over 1 million wavenumbers per second.
For the first time, the benefits of QCL technology will be widely accessible, especially to small and medium-sized businesses (SMEs), thanks to more effective assembly and combination procedures.
Advantages and Areas of Application of MOEMS-EC-Qcls
MOEMS-EC-QCLs are distinguished by their great spectral brilliance and broad spectral tunability in the 4–11 µm mid-infrared wavelength range. They enable whole infrared spectra to be recorded in just 1 ms and are appropriate for a variety of spectroscopy techniques, including transmission, backscattering, ATR, microfluidic, and point-of-interest spectroscopy.
As a result, MOEMS-EC-QCLs have a wide range of potential applications. For instance, they can be used in semiconductor measurement technology to ascertain the thicknesses and compositions of epitaxial layers, in process analytics to optimize chemical reactions, in process control to test coatings, in security technology to identify intoxicants or hazardous substances, and in the pharmaceutical industry for quality assurance.
Multi-Core System at Laser World of Photonics 2025
A multi-core system consisting of four semi-automatically manufactured MOEMS-EC-QCL modules and related peripherals will be presented by Fraunhofer IAF at this year's Laser World of Photonics in Munich from June 24 to 27 to showcase the recently developed manufacturing and combination processes for MOEMS-EC-QCL modules. It will be displayed at the Fraunhofer joint booth in Hall A3, booth 431, and other highlights from the optoelectronics business unit.
BMFTR Project AIRLAMet
The findings came from the German Federal Ministry of Research, Technology, and Space's (BMFTR) AIRLAMet project (Electro-optical measurement system for inline production control in chip fabrication).
Under the direction of Sentronics Metrology GmbH, the project's partners, Fraunhofer IAF, Fraunhofer IPMS, and Sacher Lasertechnik GmbH, are developing a tool to measure the composition and thickness of thin functional layers in semiconductor manufacturing. A first step toward accomplishing the project's goals is the supply of a high-performance and reasonably priced laser light source for the measuring equipment.
The Federal Ministry for Research, Technology, and Space (BMFTR) funds the AIRLAMet project.