[Izumi, Sugimoto, Yokogawa]

We measured the frequency of the KAGRA main laser and the Prometheus(Xarm) with respect to the laser crystal temperature. We used wavelength meter(Highfinesse WS Ultimate 30) for this measurement. Blue marker is the KAGRA main laser and green marker is the Prometheus for Xarm. For reference, I plotted the data of Mephisto in U. Toyama which was measured last year as red marker.

In order to take beatnote between the main laser and the Prometheus, it is nessesary to bring frequencies of two laser closer. However it seems that the frequencies approach only when the main laser temperature is very high and the Prometheus temperature is very low. Furthermore, the overlap range is narrow.