Abstract
A tunable Fabry-Perot interferometer (TFPI)-type wavelength filter designed for the long-wavelength infrared (LWIR) region is fabricated using micro electro mechanical systems (MEMS) technology and the novel polydimethylsiloxane (PDMS) micro patterning technique. The structure of the proposed infrared sensor consists of a Fabry-Perot interferometer (FPI)-based optical filter and infrared (IR) detector. An amorphous Si-based thermal IR detector is located under the FPI-based optical filter to detect the IR-rays filtered by the FPI. The filtered IR wavelength is selected according to the air etalon gap between reflectors, which is defined by the thickness of the patterned PDMS. The 8 μm-thick PDMS pattern is fabricated on a 3 nm-thick Al layer used as a reflector. The air etalon gap is changed using the electromagnetic force between the permanent magnet and solenoid. The measured PDMS gap height is about 2 μm, ranging from 8 μm to 6 μm, with driving current varying from 0 mA to 600 mA, resulting in a tunable wavelength range of 4 μm. The 3-dB bandwidth (full width at half maximum, FWHM) of the proposed filter is 1.5 nm, while the Free Spectral Range (FSR) is 8 μm. Experimental results show that the proposed TFPI can detect a specific wavelength at the long LWIR region.
Highlights
Infrared spectrometers that can detect specific wavelengths in the infrared (IR) region are required for various applications, such as in automobiles, military, medical treatment, and analysis, and there is an increased demand for improvements in spectroscopic technology
The bolometer bolometer was was fabricated fabricated under the lower reflector, so that when light with a specific wavelength that penetrated the under the lower reflector, so that when IR light with a specific wavelength that penetrated Fabry-Perot interferometer (FPI)
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Summary
Infrared spectrometers that can detect specific wavelengths in the infrared (IR) region are required for various applications, such as in automobiles, military, medical treatment, and analysis, and there is an increased demand for improvements in spectroscopic technology. In recent years, various studies have focused on IR detection sensors using IR spectrometry [1,2,3]. Some studies focus on the tunable Fabry-Perot interferometer (TFPI) to finely control the wavelength range while using optical filters [4,5,6]. TFPI optical filters offer controllable optical wavelength resolutions and are employed as core components in Wavelength Division Multiplexer (WDM) networks [7], different methods of spectroscopy [8,9], and sensor applications [10,11,12]. MEMS (Microelectromechanical systems)-based TFPI filters are widely studied, owing to their advantageous features, including miniaturization, batch processing, cost-effectiveness, and insensitive polarization working.
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