Terahertz time-domain spectroscopy has been used to characterise the refrac
tive index and absorption coefficient of samples fabricated using the negat
ive photoresist SU-8, in the frequency range 0.1-1.6THz. At a frequency of
1THz, the corresponding dielectric constant and dielectric loss tangent are
2.9 and 6.3 x 10(-6), respectively.