Low phase noise diode laser oscillator for 1S-2S spectroscopy in atomic hydrogen

Area of Science:

• Atomic Physics
• Laser Spectroscopy
• Quantum Optics

Background:

• Achieving high spectral purity in diode lasers is crucial for precision measurements.
• Phase noise in laser systems can degrade performance in sensitive spectroscopic applications.
• Stabilizing lasers to reference cavities is a standard technique for noise reduction.

Purpose of the Study:

• To report a low-noise diode laser oscillator at 972 nm.
• To achieve a high fraction of laser power in the carrier.
• To evaluate the laser's performance in atomic hydrogen spectroscopy.

Main Methods:

• Active stabilization of a diode laser oscillator to an ultrastable, vibrationally and thermally compensated reference cavity.
• Design of a 20 cm long external cavity diode laser with an intracavity electro-optical modulator to increase carrier power.
• Recording 1S-2S spectra in atomic hydrogen using the stabilized laser.

Main Results:

• The diode laser oscillator achieved 99.9% fractional power in the carrier.
• The root-mean-square (rms) phase noise was measured to be 1 mrad² within a 10 MHz bandwidth.
• No significant loss of excitation efficiency was observed in atomic hydrogen 1S-2S spectroscopy.

Conclusions:

• The developed low-noise diode laser oscillator is suitable for high-precision atomic spectroscopy.
• The high carrier power and low phase noise minimize detrimental effects in multi-photon excitation processes.
• This laser system advances capabilities for fundamental physics measurements in atomic hydrogen.