Mirny continous frequency change

choelzl

I was playing around a bit with the mirny we just got and was thinking about using it for a laser lock. However if I now set the frequency, it switches of for a few us, which throws the laser out of lock. Now i was wondering if this can somehow avoided. Does someone has experience with this?
Essentially the code

  while True:
            channel.set_frequency(f)
            delay(10*aq.ms)

produces the following spectrum, there you can see the off times in between.

rjo

It's a pll. It's always out of lock if you change parameters. Maybe you can reduce the impact by changing the command sequence. Have a look at the chip datasheet.

choelzl

Yes but I hoped someone has maybe already invested some time in optimizing the lock time.

rjo

ACK.
IIRC there is something like an automatic output blanking of the PPL chip when re-locking after chaning parameters. It may be possible to disable that and observe the relocking.

choelzl

I got some first results by setting the update timeout to a very low value. This gets rid of the dead time but I have not tested yet what it means for phase and frequency stability but I can imagine it is quite unstable.

        self.regs[9] = ADF5356_REG9_TIMEOUT_UPDATE(
            self.regs[9], int32(10)
        )