Fiber-Based 589 nm Laser for Sodium Guide Star

摘要

This report results from a contract tasking University of Southampton as follows: The work will entail the construction of the required sub-assemblies, their integration into the laser source, and the exploration and adjustment of parameters in order to obtain adequate performance. We have reasonable versions of several of the needed fibers, and though we are likely to have to fabricate new fiber, this requirement is assumed to be modest. The 1060 nm pulsed diode-based seed source is based on our previous work in the field. A simple low-power pre-amplifier (YDFA) with high gain efficiency will be built with all-fiber technology and core-pumping. The 1178 nm Raman fiber seed source requires appropriate highly nonlinear fiber to be acquired or fabricated and, more challenging, narrow-linewidth FBGs to be written. A cladding-pumped Yb-doped fiber laser with a few watts of output power will be assembled, to be used as a pump source for the Raman seed source. Fiber for the high-power amplifier and Raman converter will be fabricated as necessary. We hope to be able to use modest-size, strictly single-mode cores, as this will simplify system integration (splicing in particular). We plan to use a pre-configured frequency-doubler which requires minimum effort on our part. Besides fabrication and assembly of the source, most effort will go into characterization and evaluation of components, sub-assemblies, and the system as a whole. This is important to identify the right operating point, which is relatively narrow in a pulsed system based on nonlinear conversion. It will also enable us to assess the power-scaling potential and overall potential of the approach.