Participants: Marco, Eleonora

We have characterized the PZT gain of the laser AUX2 as function of the frequency.

The measurement has been done by monitoring (with the spectrum analyzer HP 8563E) the width of the beating note of the two axiliary lasers, when a modulation was sent to the PZT of AUX2.

The first attached plot shows the PZT gain as a function of the frequency from 1 kHz to 170 kHz. Its value is almost constant up to100 kHz. After that, the piezo resonanaces start to appear.  We remark that the gain at low frequency is about 1.8 MHz/V while from the laser spec we expected 1 MHz/V.

As an exemple, in the second attachment is shown the enlarged beating note observed when sending to AUX2 piezo a modulation at 60 kHz. The width of the beating corresponds to twice the PZT gain at that modulation frequency.