*3.4. Performance Summary and Comparison*

Although multiband thermal detectors show lower responsivity and higher NEP than multiband semiconductor detectors, they exactly constitute compact multiband structures, allow a wide spectrum detection, and avoid multiband impedance matching. Therefore, the proposed triple-band THz thermal detector and several published thermal detectors are summarized and compared in Table 1. A quad-band thermal detector consisting of an antenna and an NMOS sensor is designed to operate at 0.546 THz, 0.688 THz, 0.78 THz, and 0.912 THz [26]. It obtains better characteristic results, but operation at higher frequencies is preferable, thus THz thermal detectors operating above 1 THz have been proposed. Thermal detectors operating at three single frequencies of 1 THz, 2.9 THz, and 28.3 THz are composed of three discrete detectors with worse characteristic results [24]. In addition, compared with triple-band detectors in [27,28], the proposed detector applied an octagonal ring antenna as an alternative absorbing structure, showing a slight difference in performance due to the processing error or measurement error. Besides, the proposed detector, which was measured at three operation frequencies, also highlighted the concept of collaborative designs and detailed analysis. Although performance measurements of the proposed detector were finished at three operation frequencies, we would like to obtain traces of the output voltage from an oscilloscope or source meter at a certain chopping frequency for the purpose of visualizing in-time performances greatly in the future. Furthermore, in future work, we also prefer to compare performances at different ambient temperatures in order to further estimate the best possible performances.


**Table 1.** Performance summary and comparison.

\* based on simulation results.
