Broadband performance limits of ultra-thin lenses using time-domain analysis

Area of Science:

• Optics
• Wave Phenomena
• Materials Science

Background:

• Thin lenses are commonly used for focusing light, but their performance can be limited.
• Variations in the time of flight of light through a lens can distort the wavefront.
• The temporal coherence of light sources plays a crucial role in optical system performance.

Purpose of the Study:

• To investigate the fundamental limitations of thin lenses in focusing broadband light.
• To analyze the impact of temporal coherence on lens performance metrics like the Strehl ratio.
• To determine if these limitations apply to both traditional diffractive optical elements and modern metalenses.

Main Methods:

• Utilized effective medium theory to model the optical properties of thin lenses.
• Employed scalar diffraction theory to analyze wave propagation and focusing.
• Performed time-domain analysis to understand the influence of light's temporal characteristics.

Main Results:

• Thin lenses cannot fully compensate for time-of-flight variations to maintain an intact wavefront.
• The temporal coherence of the illumination imposes hard limits on the achievable Strehl ratio.
• These performance limitations are inherent and affect both diffractive optical elements and metalenses.

Conclusions:

• The effectiveness of thin lenses is fundamentally constrained by the temporal coherence of broadband light.
• Interference effects, crucial for focusing, are diminished by limited temporal coherence.
• Future optical designs must account for these coherence-imposed limits for improved performance.