Brewster-coupling-based thin film filter design for wide-angle high-efficiency phosphor emission

Area of Science:

• Optics and Photonics
• Materials Science
• Optical Engineering

Background:

• Traditional bandpass filters often face limitations in achieving optimal transmittance and wide angular reflectance.
• Laser Activated Remote Phosphor (LARP) systems require efficient light extraction for enhanced performance.
• Existing LED-phosphor models can benefit from improved optical filtering solutions.

Purpose of the Study:

• To propose and validate a novel bandpass filter design for LARP applications.
• To leverage the Brewster angle for optimal transmittance and enhanced reflectance properties.
• To compare the performance of this new filter design against conventional dichroic filters in LED-phosphor models.

Main Methods:

• A bandpass filter design method utilizing the Brewster angle as the passband was developed.
• Optical thin film filter samples were designed using consistent criteria, objective functions, and optimization algorithms.
• A 50-layer filter design was implemented for both LARP and LED-phosphor configurations.

Main Results:

• The proposed design achieves 100% transmittance at the Brewster angle, an optimal value.
• The filter demonstrates superior stopband reflectance over a wide angular range compared to dichroic filters.
• Optical losses were measured at 23.7% for the LARP filter and 26.0% for the LED-phosphor filter.

Conclusions:

• The Brewster angle-based bandpass filter design offers significant advantages for LARP systems.
• This novel approach enhances light extraction efficiency and reduces optical losses.
• The design shows promise for improving the performance of phosphor-based lighting and display technologies.