Shalika, Mitsuhashi-san,

This elog covers the following aspects:

1. Setting up EOM after LB1901C

2. Setting up lens LA1986C after EOM and beam fitting after it. 

3. Setting up Faraday Isolator after LA1986C.

(Details below)

1. a. In continuation of our setup, we installed a HWP (to optimize the polarisation of the beam entering the EOM). To find the desired angle, we set a PBS after the HWP and checked for the transmitted power. (The PBS was removed before installing EOM) The power was observed at various angles of rotation of HWP to find the optimum position (see image 1 for graph). The angle was set at 117.5° where the power of the beam was observed to be 3.91 mW. (See image 2 for setup)

  b. We installed the EOM at the minimum waist position from the lens (LB1901C) after the HWP. Although we needed to supply 6.177V for 1 rad phase shift, we could only supply 5 Vp-p. This was a limitation of the function generator. The observed beam power after EOM was 3.768 mW.

2. We then installed a mirror and set up a lens of f=125mm. To optimize beam propagation through Faraday Isolator, we observed the beam profile after the lens to find the minimum waist position. The minimum waist was found at 194.7 mm and 175.6 mm for major and minor radius respectively. (see graph 3 for details)

3. The Faraday Isolator(FI) was installed at the minimum waist obtained from 175 mm from lens. The power was observed after the FI to find its optimized location and was found to be 3.390 mW. For efficient reflection from the surface of the next mirror, we installed a HWP after the FI. (see setup in the image 4)

Next Step:

1. We will optimize the angle of HWP after FI.

2. We will install the last lens before the cavity.