We investigated the laser-induced signal by varying the angle between the antenna axis and the linearly polarized electric field vector of the incident laser radiation for different temperatures between T=77 K and T=335 K.
As reported previously1,2 the recorded voltage consists of a polarisation dependent and a polarisation independent part. The period between the two maxima in the curve is 180 degree. The difference between a voltage peak and a voltage valley is found to be half of the maximum total signal. Experiments performed in the past1 with MOM diodes of different contact sizes (1 μm2 and 0.12 μm2) demostrated that the polarisation dependence is strongly related to the size of the contact area and was therefore attributed to antenna coupling.
For the experiments described in this abstract the MOM diodes were heated to 335 K and cooled to T=77 K. The part of the response of the diode not affected by the polarisation decreases up to 55% whilst the polarisation dependent part exhibits no change with temperature or slightly increases for some diodes. These experiments confirm definitely that the polarisation dependent part of the signal is due to antenna coupling whereas the polarisation independent part is mainly caused by thermal effects.