Study On NbN Hot Electron Bolometer Mixer

In the region of astronomy application, terahertz detector on HEB mixer has developed for twenty years. HEB is a planar guide with tiny parasitic reactance. TREND spectrometer implemented in south pole was maded by HEB technology.The hyterodyne terahertz detector on superconducting NbN material has extremly high senstivity whose DSB temperature is approaching the quantum limit. The detector is used in receive and Analysis of weak submillimeter wave emitted by cosmic radiation and terahertz wave which has a important significant on cosmic radiation. This technology introduced by the dectector is called HEB hyterodyne mixer that can be classified as electron-phonon interaction cooling (p-HEB) and electron diffusion cooling (d-HEB) pricinple. In the actual amplication, if the length of microbridge is too short (make the time of electron diffsion shorter than electron-phonon interaction's), the Josephson noise would be exssecively high which could submerge signal electrical current. In consequence, in this dissortation we only discuss the former. So far, however, there is no theory that can thoroughly explain the charactistics of noise temparature , conversion gain, I-V curve, size effect, stability and immeditite frequency. Hot-spot Model is now common model which can match all above characteristics whereas the difference of theory and experimental data would largen when LO frequency is larger than energy gap frequency which would cause abnormal modulation of Hot-spot length, which would be more obvious as the LO frequency increases. We focus on that a theory model could be introduced to match all charecteristics and experimental data which would provide theoretical predictions of focul plane array employed by terahertz imaging.At last we analyse the spetrum transimission of Zitex filter in NbN HEB mixer system by Time-domain spectrometer and Fourier transform infrared spectrometer.