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Títol: MINIATURIZED FREQUENCY DOUBLED DPSS LASER Miniaturized frequency doubled DPSS Laser optimized with solderjet with bumping technology for aerospace applications

Director/a: LLANES PITARCH, LUIS MIGUEL

Departament: CEM

Títol: MINIATURIZED FREQUENCY DOUBLED DPSS LASER Miniaturized frequency doubled DPSS Laser optimized with solderjet with bumping technology for aerospace applications

Data inici oferta: 09-05-2013     Data finalització oferta: 09-01-2014


Estudis d'assignació del projecte:
    Tipus: Individual
     
    Lloc de realització: Fora UPC    
     
            Supervisor/a extern: Sergi Ferrando Margalet
            Institució/Empresa: MONOCROM, SL
            Titulació del Director/a: PhD Physics
     
    Paraules clau:
    soldering, green laser, aerospace applications
     
    Descripció del contingut i pla d'activitats:
    The Master Thesis proposed will be the result of a project developed by the laser devices company Monocrom in collaboration with the Fraunhofer Institute for the ESA Exomars mission.

    Laser devices used in current or past space missions are built by the assembly of their components mechanically or gluing them. Those methods have been enough to date, when Exomars mission required a very small and precise green laser device for Raman spectroscopy.

    The laser that is being developed is a solid state green laser that has to meet strict requirements on precision. By definition, green lasers are non linear devices. This property implies that lasers are hard to assemble and, also, that every little misalignment becomes critical.

    The actual laser prototype is glued. However, the objective is to have a completely adhesive free laser. Although the adhesives used have a low outgassing rate space certified by the NASA, glues have been identified as a source of uncertainties that affect final precision, efficiency and reliability of the device. For that reason, next step is to use soldering techniques to assemble the laser. The Franhoufer Institute has developed an exhaustive study on solderjet bumping technology to evaluate their application for the green laser. From this investigation, the first resonators have been assembled within a collaboration frame between Monocrom and the Fraunhofer Institute. After that, it is concluded that soldering may be considered a feasible solution for the problems associated with the use of glues. Those problems come from misalignments due to curing process, thermal changes or outgassing, for example.

    This work will include the review and assessment of the problems found with the first prototypes assembled, which led to the need of approaching soldering techniques for the assembling process. Furthermore, it deals with the process of performing the first soldering tests, and the results obtained and their comparison with the results of glued prototypes. However, some other issues solved during the development of first prototypes will also be described, since the author was involved in solving them, although not being a direct reason for removing the adhesives from the assembly process. As a summary, the main point of the project proposed as Master Thesis is to closely follow the assembly process and performance of the soldered laser prototype. The later includes a comparison of the laser properties and characteristics with those ones of a glued laser, to verify that the soldering improves laser stability, repeatability and robustness as expected. Achievement of this goal will result in the first laser device for space applications that has been assembled using soldering techniques.

     
    Overview (resum en anglès):

    This master thesis presents the research performed to reach the optimum assembling technique for the miniaturized green laser for the ESA Exomars space mission. The strong requirements on optical performance of the laser, in combination with the space resistance needs, make a challenge to assemble this laser. The objective of this master thesis is to demonstrate that assembling the laser using the solderjet soldering technology studied and developed by Fraunhofer IOF is the solution for the laser to meet requirements on spectrum repeatability and stability, as well as satisfying the strict optical requirements. The results obtained show the success achieved in both objectives. Stability results obtained are in the range of 0,007nm while requirements allow a wider deviation of less than 0,040nm during 20 minutes. Linewidth of the soldered resonators also meet requirements, being <30pm when optimal condition for the laser operation is found. Moreover, repeatability achieved is a change of 0,004nm of the central wavelength along different days, while glued prototypes showed a bigger change of 0,020nm even during same day tests. In conclusion, the actual phase of the project is finished with the results obtained and the soldered green laser becomes a stronger candidate for next Exomars project validation phases.

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