Kinoforms designed to produce different fan-out patterns for two wavelengths

Area of Science:

• Optics and Photonics
• Diffractive Optics
• Wave Phenomena

Background:

• Kinoforms are diffractive optical elements capable of manipulating light wavefronts.
• Achieving wavelength-specific optical responses from a single diffractive element is a significant challenge.

Purpose of the Study:

• To design and demonstrate kinoforms that produce distinct fan-out patterns for different wavelengths (green and red).
• To explore and compare different techniques for wavelength discrimination in kinoform design.

Main Methods:

• Utilized a design method based on the full scalar wave equation.
• Employed optimal-rotation-angle optimization for kinoform design.
• Investigated focusing-defocusing for near-field patterns and active suppression or increased phase modulation for far-field patterns.

Main Results:

• Successfully designed three kinoforms demonstrating wavelength discrimination.
• Near-field pattern discrimination was achieved using focusing-defocusing.
• Far-field pattern discrimination was achieved via active suppression or increased phase modulation (>2pi rad).
• Manufactured kinoforms qualitatively matched design predictions.

Conclusions:

• Kinoforms can be engineered for wavelength-specific fan-out patterns.
• The choice of technique for color discrimination depends on whether near-field or far-field patterns are desired.
• The scalar wave equation and optimization methods are effective for designing such wavelength-discriminating kinoforms.