Miniaturized frequency doubled DPSS laser soldered for space applications

Abstract

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.