Recently, the research team led by Fraunhofer Izm announced the development of a non adhesive, space saving, stable and reliable CO2 laser welding process, which can be used to fix optical fibers on fused silica glass substrates.
It is reported that this work is carried out around the "picweld" Eurostar project, and the participants include researchers from Fraunhofer Izm and their partners lionix international BV, phix photonics assembly and ficontec service GmbH. At present, the process has been integrated into an automated calibration system, and its high reproducibility and scalability have verified the industrial maturity, making the glass to glass connection technology very attractive in commercial applications.
In the past, miniaturized systems based on photonic integrated circuits (PICS) can be easily used to understand the role of visible light in biological processes. However, this system requires highly stable optical fiber connection, and the commonly used adhesive itself has softness, which will cause the position of the components to change over time, and will also produce interference points between the two layers of glass. This will lead to signal attenuation, and as the adhesive ages, the optical fiber connection will become fragile and unstable. In the long-term process of adhesive bonding, optical degradation will occur and cause quite high optical transmission loss, which is precisely a very fatal loophole in the application of key life sciences and medical technology.
In response to these problems, the cooperative research team developed a new process for manufacturing glass transparent joints based on CO2 laser welding, making it simpler, stronger and more durable. The new automation system can realize adhesive free interface and efficient coupling of waveguide integrated pics welded optical fibers.
Researchers still need to overcome many challenges before this process can be truly applied. Due to the different volume of glass fiber and substrate, the heat capacity of these two parts is not equal. This difference leads to very different heating and cooling behaviors, which may lead to a series of problems, such as deformation and cracking during cooling. The solution of the above photon experts is to uniformly preheat the substrate through a separate and adjustable laser, so as to realize the melting stage of the fiber and the substrate at the same time.
It is reported that the new automatic alignment system is equipped with thermal process monitoring up to 1300 ℃, accurate to 1 μ M positioning system, image recognition process and control software. During the project, this system is used to weld joints, so as to test its function and initial process.
After the completion of the "picweld" project in 2021, the first follow-up project was launched immediately, which will develop new fiber coupling technologies for collimators, waveguide chips and multi lens arrays.
Dr. Alethea Vanessa Zamora of Fraunhofer Izm explained, "through our CO2 laser welding system, we have expanded the process behind the existing principles. Based on its highly automated potential, customers can now use pics with the highest coupling efficiency. Such industrial integration means a leap in the application field of biophotonics, as well as quantum communication and high-performance photonics."
Source: OFweek laser network
