A cryogenic bolometer has been fabricated using a bundle of single-walled carbon nanotubes as absorber. A bolometric response was observed when the device was exposed to radiation at $110\mathrm{GHz}$ . The temperature response was $0.4\mathrm{mV}∕\mathrm{K}$ , with an intrinsic electrical responsivity at low frequency up to ${10}^9\mathrm{V}∕\mathrm{W}$ and noise equivalent power of $3\times {10}^{-16}\mathrm{W}∕{\mathrm{Hz}}^{1∕2}$ at $4.2\mathrm{K}$ . The response is largest at input power levels of a few femtowatts and decreases inversely proportional to the input power. Low frequency noise shows a $1∕f$ dependence.

Two series/parallel arrays of ten cold-electron bolometers with superconductor-insulator-normal tunnel junctions were integrated in orthogonal ports of a cross-slot antenna. To increase the dynamic range of the receiver, all single bolometers in an array are connected in parallel for the microwave signal by capacitive coupling. To increase the output response, bolometers are connected in series for dc bias. With the measured voltage-to-temperature response of 8.8 μV/mK, absorber volume of 0.08 μm³, and output noise of about 10 nV/Hz^1/2, we estimated the dark electrical noise equivalent power (NEP) as NEP = 6 * 10^-18 W/Hz^1/2. The optical response down to NEP = 2 * 10^-17 W/Hz^1/2 was measured using a hot/cold load as a radiation source and a sample temperature down to 100 mK. The fluctuation sensitivity to the radiation source temperature is 1.3 * 10^-4 K/Hz^1/2. A dynamic range over 43 dB was measured using a backward-wave oscillator, a variable polarization grid attenuator, and cold filters/attenuators.

Mesh band-pass filters for 300-, 450-, 600-, and 750-GHz central frequencies are designed and manufactured. Copper and aluminum foil and foil-clad Teflon filters were made by chemical and ionic etching methods, and an aluminum film evaporated on a kapton film was formed by the lift-off lithography method. A gold layer was electrolytically applied on copper mesh filters. Characteristics of the filters were measured in the millimeter, submillimeter, and infrared (IR) ranges. Foil filters demonstrate better characteristics at lower frequencies, while filters with evaporated films have better characteristics at upper frequencies. The smallest transmission loss was 0.13 dB. For a combination consisting of four filters, this loss was 0.9 dB. The IR radiation attenuation in a 2.5- to 25.0-μm wavelength region was no less than 11 dB per filter.