Narrowband high-reflection filters with wide and low-reflection sidebands

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• High-reflection filters are crucial optical components.
• Optimizing filter performance, especially sideband characteristics, remains an active research area.

Purpose of the Study:

• To propose and analyze narrowband high-reflection filters with a specific multilayer structure incorporating a Cr layer.
• To investigate the influence of the Cr layer and dielectric matching stacks on filter reflection characteristics, electric field distribution, and optical absorption.

Main Methods:

• Theoretical analysis of filter structures with the formula sub|H(LH)(m1)alpha L(HL)(m2)Cr(beta)M|air.
• Calculation of internal electric field distribution and optical absorption.
• Evaluation of reflection characteristics, including maximal reflectance, half-width, and sideband behavior.

Main Results:

• Matching stacks improve sideband characteristics without affecting maximal reflectance or bandwidth.
• A thicker metal (Cr) layer can lead to wide and flat reflection sidebands.
• Lowering sideband reflection requires specific matching stacks, and filter parameters (m1, m2, refractive indices) influence reflectance and bandwidth.
• Electric field intensity in the Cr layer is highest outside the central wavelength, directly impacting optical absorption.

Conclusions:

• Dielectric matching stacks are effective for enhancing sideband performance in high-reflection filters.
• The Cr layer's properties and its interaction with matching stacks are critical for controlling optical absorption and filter characteristics.
• The proposed filter design offers tunable properties for specific optical applications.