Sub-megahertz linewidth 780.24  nm distributed feedback laser for ⁸⁷Rb applications

Area of Science:

• Optoelectronics and Photonics
• Atomic Physics and Quantum Technologies

Background:

• Development of compact, high-performance semiconductor lasers is crucial for advancing quantum technologies and atomic physics applications.
• Existing laser systems often face limitations in terms of size, power, linewidth, and tunability, hindering their integration into miniaturized experimental setups.

Purpose of the Study:

• To demonstrate a Gallium Arsenide (GaAs)-based distributed feedback (DFB) semiconductor laser optimized for atom cooling applications.
• To achieve a narrow spectral linewidth and high output power suitable for precise atomic manipulation, specifically targeting the D2 ⁸⁷Rubidium (Rb) transition.

Main Methods:

• Fabrication of a GaAs-based semiconductor laser incorporating a laterally coupled grating for distributed feedback.
• Integration of a mode expander and aluminum-free active layers to enhance laser performance.
• Characterization of laser output power, wavelength, linewidth, side-mode suppression ratio (SMSR), and tuning range.

Main Results:

• Demonstrated a DFB semiconductor laser operating at 780.24 nm with an output power of up to 60 mW.
• Achieved a significantly reduced linewidth of 612 kHz using a mode expander and aluminum-free active layers.
• Exhibited over 40 dB side-mode suppression ratio and a tuning range greater than 0.3 nm.

Conclusions:

• The developed GaAs-based DFB laser meets critical performance metrics for atom cooling experiments, particularly for the ⁸⁷Rb D2 transition.
• The laser's combination of high power, narrow linewidth, and tunability makes it a promising candidate for integration into miniaturized cold atom systems.
• This work contributes to the development of more accessible and portable atomic physics research platforms.