Position Sensor

Abstract

Using PDH technique to sense the vibration and the movement of the mirror driven by the noise from the environment (acoustic, thermal, etc.)

PDH is commonly used in locking to provide a means to control and decrease the laser’s linewidth, and further to stabilize the mode of the laser light. Alternatively, if a stable laser is available, the PDH technique can be used to stabilize and/or measure the instabilities in an optical cavity length.

In this proposal, we will lock the cavity by reading the error signal of reflection/transmission of the cavity and then feed it back to the input mirror, moving the mirror with a PZT. And then we can read out the cavity length change from the error signal. This sensing technique is commonly using in LVK (LIGO-Virgo-KAGRA) interferometric gravitational wave detection community, as well as quantum optomechnics.