- Laser frequency noise is one of the limiting factors to the accuracy of our interferometer readout system.
- Several methods were used to stabilize the frequency of laser.
- First is the standardized Pound–Drever–Hall(PDH) method, we use a Zerodur optical cavity as our frequency reference. On top of the PDH method, two lasers are locked to adjacent modes of the cavity via PDH, and their beat note is measured to create a feedback loop for cavity fluctuation compensation.
- Another system uses transition lines of particular gas molecules(HCN) as a frequency reference.
- Objective : All these systems are meant to provide stabilized laser sources in designated frequency regimes so that performance of our optical readout system is improved.