Transition–edge superconducting antenna–coupled bolometer

We are developing a single pixel antenna coupled bolometric detector. Our device consists of a dual slot microstrip antenna coupled to an Al/Ti/Au voltage-biased transition edge superconducting bolometer (TES). The coupling architecture involves propagating the signal along superconducting microstrip lines and terminating the lines at a normal metal resistor on a thermally isolated island where the TES is also located. The device, which is inherently polarization sensitive, is optimized for 140GHz band measurements. Dark testing of the bolometer element showed a noise equivalent power of 2.0 × 10-17 W/√Hz with a thermal conductance G ~5.5 × 10-11 W/K. The device shows an optical time constant of 1.1 ms, and gives a figure of merit NEP √τ = 6.6 × 10-19 W⋅s. The fastest time constant measured is 437µs. The NEP is consistent with the value expected from thermal noise, Johnson noise, and amplifier noise. This device shows negligible excess noise down to frequencies as low as 1 Hz