Frequency Standards and Metrology Group - Optical Division
Within the FSM-Optical Division we are undertaking several exciting
projects. On this page you will find a quick summary of each of these.
If you are interested then you can follow the links listed at the
beginning of each section to find further details, scientific
information, latest developments as well as pictures of the
experimental apparatus - please be warned that this site is only just
becoming organised and so many details are still missing. Follow these
links for pictures of the personnel and publications.
Our file server is at 220.127.116.11 (big_laser).
good fraction of our personnel are swim-crazy and you can find the best
times for each of them for swimming 1km (in either the ocean or the
pool) here.For information about teaching courses taught by Andre and John McFerran follow this link.
FREQUENCY STABILIZED LASERS FOR TESTS OF PHYSICS (Fred Baynes, Mike Tobar, Andre Luiten)
Frequency stable lasers are important in many areas of
industry and science. We are attempting to stabilize our Nd:YAG
lasers to a Fabry-Pérot cavity built from sapphire. Below
you can see the sapphire cavity that we have constructed. Two
high-reflectivity sapphire mirrors are clamped on to the ends of
the sapphire using the Aluminium clamps. In the third photograph
you can see the assembled Fabry-Pérot inside its vacuum
can (before it was assembled!). We rely on the length stability
of the sapphire to define a single frequency laser mode that may
fit between the mirrors of the cavity. The entire cavity is
temperature controlled to a very high degree and this deliver
super high frequency stability. At the moment we have an
effective frequency stability in the 10-14 domain.
Milan is building a clock based on laser cooled Rb atoms. In
the first photograph below you can see him adjusting his mirrors
that define the Magneto-Optic Trap. It is the interaction of
magnetic fields and correctly tuned laser light that cools the
atoms to a temperature of just a few millionth of a degree above
absolute zero. Milan has succeeded in cooling 20-30 million of
these atoms to this temperature. We then expose this ensemble of
cold atoms to laser light that has been emitted in a train of
ultra-short laser pulses - in fact as low as a few 10s of
femtoseconds in duration. However, the inter-pulse time is very
well controlled, and is related to some of the atomic
sub-structure of the Rb atoms. We intend to actually control the
parameters of the ultra-fast laser using the response of the
atoms. This will have the effect of building a clock that is good
for the microwave domain (in the repeated structure of the pulses
from the laser), while also being a good optical clock (in the
frequencies of light present in the ultrafast laser source).
We have constructed two complete optical frequency
synthesizers. These device allow one to create a one-to-one phase
relationship between a very high frequency optical signal, and a
lower frequency electronic signal. This lower frequency signal
can have its instantaneous phase readily measured by comparison
with other phase references. If you want to know more about this
then read the attached paper.
FIBRE LASER STABILIZATION (Clayton Locke, John
McFerran, Andre Luiten )
We have constructed a femtosecond fibre laser comb with a unique method of stabilization so that we can great simplify the device. The intention is to deploy this device for astronomical spectrograph calibration.
MICROSTRUCTURED FIBRE CLOCKS (Anna Lurie, Chris Perrella Andre Luiten, and in collaboration with University of Bath - Fetah Benabid, Phil Light)
We are constructing a number of clocks based around the loading of vapours into the hollow-cores of optical fibre so as to perform high resolution spectroscopy upon them. At the moment we are exploring iodine (Anna) and Rubidium (Chris).
High resolution Spectroscopy for Primary Thermometry (Gar-Wing Truong, Dustin Stuart, Eric May and Andre Luiten)
We are exploring the measurement of the Doppler width of intrinsically narrow spectral lines for the purpose of a new definition of temperature based on a frequency measurement.