[Tanaka,Hirose,Saito]

In accordance with the optical layout plan in klog:36730, we installed the sub-laser, HWP, PBS, and FI.
We found that the beam size at the position of the second lens was too large, so we decided to reconsider the optical layout.
 

• Following the optical layout plan in klog:36730, we installed the sub-laser, HWP, PBS, and FI (Photo 1). From right to left in Photo 1, these are the sub-laser, HWP, PBS, HWP, and FI. Using the first HWP and PBS, we constructed the optical layout with reduced laser power. The laser power will be increased during the measurements of PRCL and SRCL. Although the HWP placed in front of the FI was not included in the original optical layout plan, it was installed to match the polarization to the FI. The FI was adjusted to maximize the transmitted power; however, the power decreased significantly from approximately 27 mW before the FI to approximately 1.8 mW after the FI. Since we had not confirmed whether the laser beam was properly aligned before placing the optical components, we plan to check the beam alignment.
   
• In the calculation of the positions of the two lenses for mode matching in klog:36730, the beam radius at the position of the second lens was found to be 10.7 mm, indicating that the beam size is too large for a 1-inch (25.4 mm) lens. Therefore, we plan to recalculate the positions of the two lenses for mode matching.