We make use of a niobium film to produce a micrometric vacuum-bridge superconducting bolometer responding to THz frequency. The bolometer works anywhere in the temperature range 2-7 K, which can be easily reached in helium bath cryostats or closed-cycle cryocoolers. In this work the bolometer is mounted on a pulse tube refrigerator and operated to measure the equivalent noise power (NEP) and the response to fast (μs) terahertz pulses. The NEP above 100 Hz equals that measured in a liquid helium cryostat showing that potential drawbacks related to the use of a pulse tube refrigerator (like mechanical and thermal oscillations, electromagnetic interference, noise) are irrelevant. At low frequency, instead, the pulse tube expansioncompression cycles originate lines at 1 Hz and harmonics in the noise spectrum. The bolometer was illuminated with THz single pulses coming either from a Quantum Cascade Laser operating at liquid nitrogen temperature or from a frequencymultiplied electronic oscillator. The response of the bolometer to the single pulses show that the device can track signals with a rise time as fast as about 450 ns
Operation of a Wideband Terahertz Superconducting Bolometer Responding to Quantum Cascade Laser Pulses / S., Cibella; M., Beck; P., Carelli; M. G., Castellano; F., Chiarello; J., Faist; R., Leoni; Ortolani, Michele; L., Sabbatini; G., Scalari; G., Torrioli; D., Turcinkova. - In: JOURNAL OF LOW TEMPERATURE PHYSICS. - ISSN 0022-2291. - STAMPA. - 167:(2012), pp. 911-916. [10.1007/s10909-012-0588-5]
Operation of a Wideband Terahertz Superconducting Bolometer Responding to Quantum Cascade Laser Pulses
ORTOLANI, MICHELE;
2012
Abstract
We make use of a niobium film to produce a micrometric vacuum-bridge superconducting bolometer responding to THz frequency. The bolometer works anywhere in the temperature range 2-7 K, which can be easily reached in helium bath cryostats or closed-cycle cryocoolers. In this work the bolometer is mounted on a pulse tube refrigerator and operated to measure the equivalent noise power (NEP) and the response to fast (μs) terahertz pulses. The NEP above 100 Hz equals that measured in a liquid helium cryostat showing that potential drawbacks related to the use of a pulse tube refrigerator (like mechanical and thermal oscillations, electromagnetic interference, noise) are irrelevant. At low frequency, instead, the pulse tube expansioncompression cycles originate lines at 1 Hz and harmonics in the noise spectrum. The bolometer was illuminated with THz single pulses coming either from a Quantum Cascade Laser operating at liquid nitrogen temperature or from a frequencymultiplied electronic oscillator. The response of the bolometer to the single pulses show that the device can track signals with a rise time as fast as about 450 nsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.