Novel hot-electron bolometer mixers for submillimeter applications: an overview of recent developments

There has been a resurgence of interest in bolometers as heterodyne mixers at submillimeter wavelengths. This is due primarily to two new and innovative concepts which result in bolometers with response times fast enough to allow for intermediate frequencies (IF) of 1 GHz-10 GHz, as well as low mixer noise temperatures. These IFs are high enough for practical spectroscopy applications and thus these bolometers need to be seriously considered as heterodyne sensors. The paper reviews the basics of bolometer mixers. Then an overview is given of the basic operation of the new high speed bolometers, along with a few results which demonstrate the performance. Finally, the role these sensors may be expected to fulfil is discussed