An ultrastable laser system at 689 nm for cooling and trapping of strontium

Rydberg blockade in an ultracold strontium gas revealed by two-photon excitation dynamics

“…However, we observed a much smaller decay rate of the Rabi oscillations for smaller Rabi frequencies (∼20 µs). Such a dependence of τ on the Rabi frequency suggests homogeneous dephasing effects and may result from the characteristic phase noise distribution of our PDH-locked laser [41], where only noises at frequencies around Ω ge play the important role for the dephasing. The inhomogeneous Doppler shifts due to the finite temperature (with a Doppler width ∼ 2π× 52 kHz) have significant effects only when the power-broadened linewidth is around the Doppler one.…”

“…Our experimental setup for producing ultracold strontium gases via a two-stage magneto-optical cooling and trapping has been described previously in Refs. [39][40][41]. In brief, a three-dimension (3D) magneto-optical trap (MOT) operating on the broad |g → 5s5p 1 P 1 (≡ |i ) transition at 461 nm is loaded from a two-dimension (2D) MOT using the same transition [39].…”

“…Then, via a single-frequency repumping at 481 nm [40], atoms accumulated in the MOT magnetic quadrupole field for 5 s are transferred to a second 3D MOT (red MOT) operating on the narrow |g → |e transition with a natural linewidth of γ e = 2π× 7.5 kHz. The red MOT stage lasts for about 200 ms [41] and a crossed optical dipole trap (ODT) at 532 nm is turned on 150 ms before switching off the red MOT. Then the atoms are held in the ODT for certain time before applying Rydberg excitation pulses.…”

“…1(a). The 689-nm red beam driving the |g − |e transition is delivered from an external cavity diode laser, which is frequency locked to a passive ultra-stable cavity resulting in a linewidth smaller than 10 kHz [41]. The upper transition (|e − |r ) is driven by a UV beam at ∼319 nm, which is obtained by frequency doubling a dye laser using resonant cavity second harmonic generation [44].…”

A hybrid-integrated diode laser in the visible spectral range

“…Integrated refractive index biosensors [7] particularly benefit from integrated narrow-linewidth sources, because the use of a highly coherent source enhances the resolution of spectral detection, and, hence, lowers the detection limit [8]. Furthermore, compact and frequency-stable light sources in the visible spectral range are required for atom cooling and trapping [9] in portable optical atomic clocks [10] and quantum information processors [11].…”