Availability of components is a deterniming factor in the filed of terahertz (THz) technology. In the proposed project we will investigate sensitivity limits of incoherent and coherent detection of terahertz waves in nano-bolometers based on YBCO films both in the superconducting state (77K) and at room temperature. When the size of the bolometer shrinks to the nanometer scale (100nm or less), the heat coupling to the substrate reduces drastically (proportional to the in-plane area). Using this approach, high detector sensitivity can be combined with a sub-nanosecond response time. Based on our recent results, we calculate that for incoherent detection a Noise Equivalent Power (NEP) of 10^-14-10^-13 W/Hz^0.5 can be reached for an operation temperature of 77K (this temperature can easily be reached using compact coolers), but it will provide an NEP of 10^-12W/Hz^0.5 even at room temperature, due to a high temperature coefficient of resistance (TCR) of YBCO films in the normal state. This TCR value is quite high for materials with moderate resistivity, which is needed for impedance matching of the bolometer to the antenna. Furthermore, the same devices can be used for coherent detection as well. The projected mixer gain is -10dB for the 77K operation, and -18dB for the room temperature operation. Such characteristics would place the discussed detectors as the most sensitive incoherent and coherent detectors for frequencies above 1THz which do not require LHe cooling.
Biträdande professor vid Chalmers, Microtechnology and Nanoscience (MC2), Terahertz and Millimetre Wave Laboratory
Funding Chalmers participation during 2012–2014