Directional laser emission from a wavelength-scale chaotic microcavity.

Area of Science:

• Optics and Photonics
• Laser Physics
• Nanophotonics

Background:

• Deformed cavity lasers typically show universal directionality due to chaotic ray dynamics.
• Controlling output directionality in micro- and nano-scale lasers remains a challenge.

Purpose of the Study:

• To demonstrate directional emission from deformed disk lasers with dimensions near the emission wavelength.
• To investigate the underlying mechanism responsible for directional output in these small-scale lasers.

Main Methods:

• Fabrication of deformed disk lasers with sub-wavelength dimensions.
• Analysis of far-field emission patterns for different lasing modes.
• Theoretical investigation of mode coupling and symmetry breaking.

Main Results:

• Directional emission was observed from deformed disk lasers comparable in size to the emission wavelength.
• Far-field patterns varied between different lasing modes, unlike larger deformed cavity lasers.
• Directional emission arises from weak coupling between high-quality isotropic modes and low-quality anisotropic modes.
• Chiral symmetry breaking of clockwise and counterclockwise waves is crucial for directionality.

Conclusions:

• A novel mechanism for achieving directional output in wavelength-scale lasers has been demonstrated.
• This mechanism relies on specific mode coupling and symmetry breaking, offering control over laser output.
• The findings pave the way for developing tunable and directional nanoscale light sources.