Abstract
Antenna-coupled micro-bridge structure is proven to be a good solution to extend infrared micro-bolometer technology for THz application. Spiral-type antennas are proposed in 25 μm × 25 μm micro-bridge structure with a single separate linear antenna, two separate linear antennas, or two connected linear antennas on the bridge legs, in addition to traditional spiral-type antenna on the support layer. The effects of structural parameters of each antenna on THz absorption of micro-bridge structure are discussed for optimized absorption of 2.52 THz wave radiated by far infrared CO2 lasers. The design of spiral-type antenna with two separate linear antennas for wide absorption peak and spiral-type antenna with two connected linear antennas for relatively stable absorption are good candidates for high absorption at low absorption frequency with a rotation angle of 360*n (n = 1.6). Spiral-type antenna with extended legs also provides a highly integrated micro-bridge structure with fast response and a highly compatible, process-simplified way to realize the structure. This research demonstrates the design of several spiral-type antenna-coupled micro-bridge structures and provides preferred schemes for potential device applications in room temperature sensing and real-time imaging.
Highlights
Terahertz (THz) radiation (0.1~10 THz, 1 THz = 1012 Hz), proven to have unique spectral characteristics of wide band, low energy penetration and spectral absorption [1, 2], is attractive for its wide variety of applications in molecular spectroscopy [3], disease diagnostics [4], sensing, and imaging [5, 6]
The spiral-type antennas were designed for absorption enhancement and modulation of THz micro-bolometer focal plane arrays (FPA) based on micro-bridge structures with a target frequency of 2.52 THz
The sensitive area consists of multilayer films including a support layer made of 0.4 μm silicon nitride (Si3N4) film, thermal sensitive layer (VOx thin film) with a thickness of 70 nm, and spiral-type antenna acting as THz absorption layer made of 0.05 μm aluminum (Al) thin film
Summary
Terahertz (THz) radiation (0.1~10 THz, 1 THz = 1012 Hz), proven to have unique spectral characteristics of wide band, low energy penetration and spectral absorption [1, 2], is attractive for its wide variety of applications in molecular spectroscopy [3], disease diagnostics [4], sensing, and imaging [5, 6] This frequency range has not been fully exploited to date, restricted by the dearth of THztuned sources and detectors. Photon detectors have a high sensitivity and a short response time, but they are selective in wavelength and often require refrigeration Photothermal detectors, such as room temperature pyroelectric detectors [15] and microbolometers [8, 9], absorb the energy of THz radiation and convert it to resistivity or spontaneous polarization changes of the thermal sensitive films.
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