Abstract
Laser frequency stabilisation in the telecommunications band was realised using the Pound-Drever-Hall (PDH) error
signal. The transmission spectrum of the Fabry-Perot cavity was used as opposed to the traditionally used reflected
spectrum. A comparison was done using an analogue as well as a digitally implemented system. This study forms part of
an initial step towards developing a portable optical time and frequency standard.
The frequency discriminator used in the experimental setup was a fibre-based Fabry-Perot etalon. The phase sensitive
system made use of the optical heterodyne technique to detect changes in the phase of the system. A lock-in amplifier
was used to filter and mix the input signals to generate the error signal. This error signal may then be used to generate a
control signal via a PID controller. An error signal was realised at a wavelength of 1556 nm which correlates to an
optical frequency of 1.926 THz. An implementation of the analogue PDH technique yielded an error signal with a
bandwidth of 6.134 GHz, while a digital implementation yielded a bandwidth of 5.774 GHz.