**Figure 7.**

*(a) Temporal profiles of the pump (lower trace) and the cavity enhanced SH (upper trace). Mode beating is reflected in the SH emission also. (b) 7 ns beat period indicates operation of the pump laser on two longitudinal modes (lower trace), the same is also reflected in the SH pulse (upper trace).*

of 105 cm long cavity, is seen. Upon comparison with the typical temporal profile of the emission of the pump laser (**Figure 3**), it becomes obvious that the integration of the pump laser with this external unstable cavity does in no way bring in any new feature in its temporal profile or alter the beat period. This clearly implies that the coupling of the external cavity with the pump cavity has no effect on the dynamics of the pump laser. A comparison of the time expanded second harmonic temporal profile (upper trace of **Figure 7b**) with that of the temporal profile of the pump (lower trace of **Figure 7b**) readily establishes their phase and amplitude synchronisation: a signature of the instantaneous nature of the SHG process.
