Reflection filter multilayers of metallic and dielectric thin films

Area of Science:

• Optics and Photonics
• Materials Science
• Telecommunications Engineering

Background:

• Narrowband spectral filters are crucial for fiber-optical communication systems operating between 1250 and 1600 nm.
• Multilayer filters combining dielectric and metallic films offer specific optical properties for reflection-based applications.

Purpose of the Study:

• To derive formulas relating metallic film transmittance to key filter specifications like bandwidth and rejection.
• To demonstrate how layer parameters can be optimized to meet bandwidth, rejection, and free spectral range requirements.
• To validate theoretical predictions through experimental photometric observations.

Main Methods:

• Development of theoretical formulas connecting metallic film transmittance to filter performance metrics.
• Layer parameter selection methodology for achieving desired filter specifications.
• Experimental verification using photometric observations on fabricated multilayer filters.

Main Results:

• Established relationships between metallic film transmittance and filter bandwidth/rejection.
• Demonstrated a method for choosing layer parameters to meet specific filter requirements.
• Photometric observations showed good agreement with theoretical predictions for five filters.

Conclusions:

• The derived formulas provide a valuable tool for designing narrowband spectral filters for optical communications.
• Optimization of layer parameters is effective in achieving desired filter characteristics.
• Experimental results confirm the accuracy of the theoretical models.