Michael A. Dem'YAnenko

Analytical relations for temperature response of the bolometer to periodic radiation pulses are obtained. It is theoretically shown and experimentally confirmed by the example of infrared bolometers that when detecting short radiation pulses, in contrast to the case of constant radiation, increasing the thermal conductivity of the bolometer and, accordingly, decreasing its thermal relaxation time, it is possible to significantly increase the response rate of the receiver, practically without reducing its sensitivity. The possibility of effective registration of pulsed terahertz radiation by microbolometers with a resistively coupled, thermally non-isolated antenna is considered. It is shown that such bolometers, which have increased thermal conductivity and, accordingly, reduced sensitivity to continuous-wave radiation, can be highly effective when detecting pulsed radiation with a duration shorter than the thermal relaxation time of the bolometer. On their basis, uncooled matrix detectors of pulsed terahertz radiation, characterized by a minimum detectable energy of less than 1 × 10^–12 J and a frame rate of up to 1000 Hz, can be developed.

Analytical relations for temperature response of the bolometer to periodic radiation pulses are obtained. It is theoretically shown and experimentally confirmed by the example of infrared bolometers that when detecting short radiation pulses, in contrast to the case of constant radiation, increasing the thermal conductivity of the bolometer and, accordingly, decreasing its thermal relaxation time, it is possible to significantly increase the response rate of the receiver, practically without reducing its sensitivity. The possibility of effective registration of pulsed terahertz radiation by microbolometers with a resistively coupled, thermally non-isolated antenna is considered. It is shown that such bolometers, which have increased thermal conductivity and, accordingly, reduced sensitivity to continuous-wave radiation, can be highly effective when detecting pulsed radiation with a duration shorter than the thermal relaxation time of the bolometer. On their basis, uncooled matrix detectors of pulsed terahertz radiation, characterized by a minimum detectable energy of less than 1·10^-12 J and a frame rate of up to 1000 Hz, can be developed. Keywords: microbolometer, pulsed terahertz radiation, antenna.

This work is devoted to the development of a technique for obtaining an array of multi-walled vertically aligned carbon nanotubes (VACNT) with a thickness of up to 120 μm on Si/Al2O3/Fe substrates and to the study of their absorbing properties in the THz spectral region, as well as to the assessment of their prospects as a broadband THz radiation absorber based on calculations of the spectral dependence of absorption coefficient for traditional and inverted-type bolometric devices. It is shown that the absorption of the VACNT array transferred onto the Revalpha polymer substrate reaches 70–80% in the wavelength range of 40–200 µm. Calculations show that traditional bolometers with an absorber based on VACNT have the best sensitivity at wavelengths less than 100 μm, and inverted bolometers also having a VACNT layer have the best sensitivity at wavelengths exceeding 50 μm, which makes them complementary to each other.

В статье идет обсуждение проблем, связанных с развитием технологии детекторов излучения терагерцевого диапазона. Продолжено рассмотрение состояния дел в области неохлаждаемых матричных болометрических приемников, недавний прогресс в различных методах детектирования терагерцевого излучения – ​прямого детектирования и гетеродинного детектирования. Внимание сфокусировано на преимуществах и недостатках сенсоров прямого детектирования и сенсоров с гетеродинным детектированием.

В работе обсуждаются проблемы, связанные с развитием технологии детекторов излучения терагерцевого диапазона. Рассмотрены основные физические явления и недавний прогресс в различных методах детектирования терагерцевого излучения (прямого детектирования и гетеродинного детектирования). Обсуждаются преимущества и недостатки сенсоров прямого детектирования и сенсоров с гетеродинным детектированием. В первой части рассмотрен ряд особенностей прямого детектирования и дано описание некоторых типов терагерцевых детекторов прямого обнаружения.

The absorption of terahertz radiation by a thin metal absorber in the bolometers of five different designs is analyzed. Main attention is paid to bolometers of three basic configurations: (i) conventional bolometers with a double-layer main optical cavity, (ii) conventional bolometers with an additional optical cavity, and (iii) inverted bolometers with an additional optical cavity. Analytical expressions that allow calculating the absorption spectra in all the considered bolometers are obtained. It is shown that conventional bolometers only with the main optical cavity made up of two dielectric layers, as well as conventional and inverted bolometers with both main and additional optical cavities, can have the absorptance close to unity in the terahertz range. At the same time, conventional terahertz bolometers are mainly selective, whereas inverted ones are broadband.

Application of thin metal absorbers allows one to significantly increase the absorption coefficient and sensitivity of matrix THz microbolometric detectors. It is shown that absorbers...

Application of thin metal absorbers allows one to significantly increase the absorption coefficient and sensitivity of matrix THz microbolometric detectors. It is shown that absorbers characterized by frequency dispersion of conductivity, in contrast to conventional nondispersive absorbers, can provide almost total IR absorption retaining high sensitivity in the THz range.

In this article, we present an overview of a focal plane array (FPA) with 640 × 512 pixels based on the AlGaAs quantum well infrared photodetector (QWIP). The physical principles of the QWIP operation and their parameters for the spectral range of 8–10 μm have been discussed. The technology of the manufacturing FPA based on the QWIP structures with the pixels 384 × 288 and 640 × 512 has been demonstrated. The parameters of the manufactured 640 × 512 FPA with a step of 20 μm have been given. At the operating temperature of 72 K, the temperature resolution of QWIP focal plane arrays is less than 35 mK. The number of defective elements in the matrix does not exceed 0.5%. The stability and uniformity of the FPA have been demonstrated.

The matrix method has been used to calculate the coefficients of absorption of terahertz radiation in conventional (with radiation incident from vacuum adjacent to the bolometer) and inverted (with...