[Shalika, Mitsuhashi-san]

This elog is about us trying to improve lock time. In continuation to work in elog. 

Details:

1. We tried tuning the cavity mirror alignment to increase the TEM00 mode. The amplitude of modes has improved (more because of the incident mentioned in point 2). Also, we tuned more to suppress other higher-order modes. Now the modes look as in CH2 in Fig 1. The error signal for the corresponding TEM00 mode is shown in CH1 in Fig 2. The scale for CH2 is 5V. We tried locking but it only locked to higher order modes as in Fig 3. 

2. On Tuesday evening by mistake I touched the first mirror in the optical setup outside the cavity. As a result, the transmitted beam was lost. I was able to fix the problem, and now the AOM diffraction efficiency is improved and is 57.3% (output: 6.59mW and incident:11.5mW). In the past, the efficiency was 38%. I made sure that there are no higher-order modes (shown in Fig 4)

Next Step:

We will try to tune the temperature of the laser to find the desired frequency at which TEM00 mode appears. Also, we will try to find the optimum offset voltage and keep improving the mirror alignment.