Publications

Toshiyuki Hosoya, Martin Miranda, Ryotaro Inoue and *Mikio Kozuma,
Injection locking of a high power ultraviolet laser diode for laser cooling of ytterbium atoms,
Review of Scientific Instruments 86, 073110/1-4 (2015).

[Summary] We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system does not depend on complex nonlinear frequency-doubling and can be made compact, which will be useful for providing light sources for laser cooling experiments including transportable optical lattice clocks.

Martin Miranda, Ryotaro Inoue, Yuki Okuyama, Akimasa Nakamoto, and *Mikio Kozuma,
Site-resolved imaging of ytterbium atoms in a two-dimensional optical lattice,
Physical Review A 91, 063414/1-6 (2015).

[Summary] We report a high-resolution microscope system for imaging ultracold ytterbium atoms trapped in a two-dimensional optical lattice. By using the ultraviolet strong transition combined with a solid immersion lens and high-resolution optics, our system resolved individual sites in an optical lattice with a 544-nm spacing. Without any cooling mechanism during the imaging process, the deep potential required to contain the atoms was realized using a combination of a shallow ground-state and a deep excited-state potentials. The lifetime and limitations of this setup were studied in detail.