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 130.95.156.56 (big_laser).

A 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.

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.

DUAL MICROWAVE-OPTICAL CLOCK - completed (Milan Maric, Andre Luiten)

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).

OPTICAL FREQUENCY SYNTHESIS AND MEASUREMENT (John McFerran, Andre Luiten)

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.

CALCIUM OPTICAL CLOCK (John McFerran, Andre Luiten)

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.