Control of emission spectra in quantum dot microdisk/microring lasers

Area of Science:

• Optics and Photonics
• Materials Science
• Quantum Technology

Background:

• Quantum dot microresonators are promising for laser applications.
• Controlling emission modes in microresonators is crucial for laser efficiency.
• Fabrication techniques can influence optical properties.

Purpose of the Study:

• To investigate the effect of focused ion beam milling on quantum dot microresonator emission spectra.
• To determine if focused ion beam can enhance mode selectivity in these resonators.
• To analyze changes in lasing threshold and linewidth post-milling.

Main Methods:

• Focused ion beam (FIB) milling was used to create surface modifications (pits/grooves) on quantum dot microresonators.
• Emission spectra of the microresonators were measured before and after FIB processing.
• Lasing threshold and mode linewidth were characterized.

Main Results:

• FIB milling significantly reduced the number of dominant emission modes.
• One or two modes became highly dominant, replacing a group of modes with comparable intensities.
• The linewidth of the lasing mode remained unchanged.
• A minor increase in the lasing threshold was observed.

Conclusions:

• Focused ion beam milling is an effective method for enhancing mode selectivity in quantum dot microresonators.
• This technique offers a pathway to developing more efficient and specialized microresonator-based lasers.
• The process preserves critical laser parameters like linewidth.