研究目的
To design, fabricate, and characterize silicon-based thin film Fabry-Pérot filters with distributed Bragg reflectors for enhanced performance in SWIR and MWIR spectroscopic sensing applications.
研究成果
The fabricated silicon-air-silicon DBR-based Fabry-Pérot filters achieved high performance with narrow FWHM and good transmittance in SWIR and MWIR ranges, demonstrating suitability for low-SWaP spectroscopic applications. Future work could focus on developing tunable versions and improving fabrication tolerances.
研究不足
The study used fixed cavity filters as proof of concept, not tunable ones. Measurements in the SWIR range had lower out-of-band rejection due to spectrometer limitations, and atmospheric absorption (e.g., carbon dioxide) affected some MWIR measurements. Fabrication requires tight control of tilt and bowing to avoid performance degradation.
1：Experimental Design and Method Selection:
The study involved optical and mechanical modeling using the optical matrix method and finite element modeling (FEM) to simulate filter performance, including effects of tilt and bowing. Fabrication was based on MEMS technology with a step-by-step process involving deposition, spinning, etching, and release of sacrificial layers.
2：Sample Selection and Data Sources:
Samples included 8 SWIR and 8 MWIR Fabry-Pérot filters with different fixed main air cavity lengths, fabricated on silicon substrates.
3：List of Experimental Equipment and Materials:
Equipment included a Sentech SI500D ICPCVD reactor for deposition, Brewer Science Prolift polyimide for sacrificial layers, Perkin Elmer Spectrum One FTIR spectrometer for spectral measurements, and Coventorware10.2 for FEM simulations. Materials included silicon, silicon oxide, gold, titanium, and polyimide.
4：2 for FEM simulations. Materials included silicon, silicon oxide, gold, titanium, and polyimide.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The fabrication process involved defining optical apertures, depositing DBR layers, spinning and baking sacrificial layers, depositing silicon layers, etching holes, and releasing cavities with critical point drying. Optical characterization included surface profilometry and spectral transmittance measurements.
5：Data Analysis Methods:
Data were analyzed using the optical matrix method extended for surface imperfections, with comparisons between simulated and measured transmittance, FWHM, and Q-factor.
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