Narrow-Line Cooling Light for a Magneto-Optical Trap of Erbium Atoms

by Alexander Rietzler
Abstract:
In this thesis, we describe the main steps for the production and stabilization of the laser light used to cool erbium atoms in a magneto-optical trap (MOT). The line that we use for the MOT has a narrow-line character with a 190-kHz linewidth and has a wavelength of 583 nm. To generate the light at 583 nm, we use a dye laser, operated with Rhodamine 6G. The laser light from the dye laser has a linewidth of about 1 MHz and a frequency drift of about 100 MHz/h. For MOT operation, we need to reduce the laser linewidth and to stabilize the laser on the resonance frequency for the different Er isotopes. For this purpose, we use a pre-locking cavity, which narrows the linewidth down to 45 kHz and we build a ultra low expansion (ULE) cavity for long-term frequency stability. A special and convenient feature of our stabilization scheme is that it allows locking of the cooling light on the atomic transition of each Er isotope in a very straightforward manner – it can in fact bridge the isotope shifts, corresponding to several GHz. The part of our locking setup that is responsible for long-term frequency stability is based on the Pound-Drever-Hall locking technique in combination with a home-build ULE cavity. This cavity is made of ultra low expansion glass, which we cool down to the zero-expansion temperature. At this temperature, the thermal expansion of the cavity is minimized. By stabilizing the laser to the ULE cavity, we reduce the long-term drift to 0.16 Hz/s. Using this light, we cooled down the five most abundant erbium isotopes to 15μK in the MOT, and recently we achieved the first BEC of erbium atoms.
Reference:
Narrow-Line Cooling Light for a Magneto-Optical Trap of Erbium Atoms,
Alexander Rietzler,
Master’s Thesis, 2012.
Bibtex Entry:
@article{RietzlerMSc,
  title = {Narrow-Line Cooling Light for a Magneto-Optical Trap of Erbium Atoms},
  author = {Rietzler, Alexander},
  journal = {Master's Thesis},
  year = {2012},
  month = {Oct},
  abstract = {In this thesis, we describe the main steps for the production and stabilization
              of the laser light used to cool erbium atoms in a magneto-optical trap (MOT). The
              line that we use for the MOT has a narrow-line character with a 190-kHz linewidth
              and has a wavelength of 583 nm. To generate the light at 583 nm, we use a dye laser,
              operated with Rhodamine 6G. The laser light from the dye laser has a linewidth of 
              about 1 MHz and a frequency drift of about 100 MHz/h. For MOT operation, we need to
              reduce the laser linewidth and to stabilize the laser on the resonance frequency for
              the different Er isotopes. For this purpose, we use a pre-locking cavity, which narrows
              the linewidth down to 45 kHz and we build a ultra low expansion (ULE) cavity for long-term 
              frequency stability. A special and convenient feature of our stabilization scheme is that
              it allows locking of the cooling light on the atomic transition of each Er isotope in a 
              very straightforward manner - it can in fact bridge the isotope shifts, corresponding to
              several GHz. The part of our locking setup that is responsible for long-term frequency 
              stability is based on the Pound-Drever-Hall locking technique in combination with a home-build
              ULE cavity. This cavity is made of ultra low expansion glass, which we cool down to the zero-expansion
              temperature. At this temperature, the thermal expansion of the cavity is minimized. By
              stabilizing the laser to the ULE cavity, we reduce the long-term drift to 0.16 Hz/s.
              Using this light, we cooled down the five most abundant erbium isotopes to 15μK in the
              MOT, and recently we achieved the first BEC of erbium atoms.},
  url = {http://www.erbium.at/FF/wp-content/uploads/2015/10/master_alexander_rietzler.pdf},
}