Manipulation of lasing modes in a circular-side octagonal microcavity laser with a spatially distributed current...

Area of Science:

• Optoelectronics
• Semiconductor devices
• Photonics

Background:

• Microcavity lasers offer compact and efficient light sources.
• Whispering-gallery (WG) modes in microcavities exhibit high quality factors and distinct field patterns.
• Controlling lasing modes in microcavity lasers is crucial for advanced applications.

Purpose of the Study:

• To propose and demonstrate a circular-side octagonal microcavity (COM) semiconductor laser.
• To investigate the manipulation of lasing modes using spatially distributed current injection.
• To achieve selective excitation of specific WG modes.

Main Methods:

• Fabrication of a COM semiconductor laser with two separated p-electrodes for independent current injection.
• Experimental and simulation analysis of whispering-gallery modes (quadrilateral and octagonal).
• Applying spatially distributed current injection to control mode selection and suppression.

Main Results:

• Simultaneous lasing of quadrilateral and octagonal WG modes with equivalent current injection.
• Observed degeneracy removal of quadrilateral modes with inequivalent current injection.
• Achieved suppression of quadrilateral modes and single-octagonal-mode lasing by un-injecting or negatively biasing one electrode region.

Conclusions:

• Spatially distributed current injection effectively manipulates lasing modes in COM semiconductor lasers.
• The distinct field patterns of WG modes allow for selective mode control.
• This technique enhances the practical applicability of microcavity lasers.