Attached is a plot summarising the behaviour of the front end laser pump diodes.
The oscillation in the output power has been observed before and I'm not sure
what it is caused by.  I had thought that it might be due to an oscillation in
the PID loop controlling the pump diode temperature, however it's not visible
in the TEC signals (D[1-4]TEC).

We still have a reasonable amount of headroom for the pump diodes.  At the
moment the diode current is ~51.5 A.  The maximum is 65 A.