Microcavity enhanced directional transmission through a subwavelength plasmonic slit

Area of Science:

• Photonics
• Plasmonics
• Optical Metamaterials

Background:

• Subwavelength plasmonic slits offer unique light manipulation capabilities.
• Achieving highly directional transmission through these structures remains a challenge.
• Optical microcavities can enhance light-matter interactions and control wave propagation.

Purpose of the Study:

• To numerically investigate the effect of optical microcavities on light transmission through subwavelength plasmonic slits.
• To enhance the directional transmission of light in the normal direction.
• To explore the impact of microcavities on impedance matching and resonant transmission.

Main Methods:

• Numerical simulations were employed to model the optical response of the proposed structure.
• The structure consists of a subwavelength plasmonic slit surrounded by multiple optical microcavities.
• Parametric studies were conducted to optimize the microcavity design and placement.

Main Results:

• The integration of microcavities significantly enhanced the directional transmission of light through the plasmonic slit.
• An optimized structure with microcavities demonstrated approximately 16 times larger transmission cross-section per unit angle in the normal direction compared to a reference slit.
• The microcavities improved impedance matching, leading to enhanced coupling between free-space waves and the slit mode.
• The operational frequency range for high emission in the normal direction was found to be broad.

Conclusions:

• Compact structures incorporating optical microcavities at the entrance and exit sides of subwavelength plasmonic slits can achieve greatly enhanced directional transmission.
• Microcavities are effective in increasing resonant transmission enhancement and improving impedance matching for efficient light coupling.
• The proposed design offers a promising approach for developing efficient directional light emitters and manipulators.