Efficient pumping of Rb vapor by high-power volume Bragg diode laser

Area of Science:

• Atomic, Molecular, and Optical Physics
• Laser Physics and Technology

Background:

• Narrow-linewidth lasers are crucial for high-resolution spectroscopy and atomic physics.
• External cavity diode lasers offer improved spectral purity over free-running devices.
• Volume Bragg gratings (VBGs) provide a compact and robust method for wavelength selection and stabilization.

Purpose of the Study:

• To develop a narrow-linewidth, tunable continuous-wave (cw) laser diode at 780nm.
• To investigate the performance of a VBG-based external cavity laser.
• To assess the laser's efficiency and absorption characteristics in Rubidium (Rb) vapor.

Main Methods:

• A 2W cw laser diode (LD) was coupled to an external cavity incorporating a reflecting volume Bragg grating (VBG).
• Spectral width was measured using a high-resolution spectrometer.
• Wavelength tuning was achieved via thermal control of the VBG.
• Absorption measurements were performed using Rb vapor.

Main Results:

• The VBG-stabilized LD achieved a spectral width of 7GHz (full width at half-maximum) at 780nm.
• The output power of the VBG laser was over 90% of the free-running LD power.
• A tuning range of 300pm was demonstrated through thermal VBG control.
• Over 95% absorption of the laser radiation by Rb vapor was observed.

Conclusions:

• External cavity VBG technology enables narrow spectral width and tunability in diode lasers.
• The developed laser system exhibits high efficiency and strong absorption in Rb vapor.
• This laser is suitable for applications requiring precise wavelength control and high absorption, such as atomic spectroscopy and laser cooling.