Hyperfine structure measurement of rubidium atom and tunable diode laser stabilization by using Sagnac interferometer

Area of Science:

• Atomic Physics
• Laser Spectroscopy
• Optical Interferometry

Background:

• Precise laser frequency control is crucial for high-resolution spectroscopy.
• Rubidium D2 lines offer well-defined atomic transitions for calibration.
• Fabry-Perot interferometers and Sagnac interferometers are standard tools in optical measurements.

Purpose of the Study:

• To measure the free spectral range (FSR) of a Fabry-Perot interferometer using Rubidium D2 lines.
• To determine the linearity of laser frequency tuning.
• To stabilize laser frequency and measure the hyperfine structure of Rubidium atoms.

Main Methods:

• Utilizing Rubidium saturated absorption spectra for D2 transition lines.
• Employing a Fabry-Perot interferometer to measure the free spectral range.
• Using a Sagnac interferometer for laser stabilization.
• Applying the tilt locking method for hyperfine structure measurement.

Main Results:

• The free spectral range (FSR) of the Fabry-Perot interferometer was successfully measured.
• Laser frequency tuning linearity was accurately determined.
• Laser frequency was stabilized to the sub-megaHertz level.
• The hyperfine structure of the 85Rb atom was measured with high precision.

Conclusions:

• Rubidium saturated absorption spectra are effective for Fabry-Perot FSR measurements.
• Sagnac interferometer provides robust laser stabilization at the sub-megaHertz level.
• The tilt locking method offers an alternative to conventional spectroscopy for hyperfine structure analysis.