  For terahertz (THz) wave applications, tunable and rapid modulation is highly
required. When studied by means of optical pump-terahertz probe spectroscopy,
single-walled carbon nanotubes (SWCNTs) thin films demonstrated ultrafast
carrier recombination lifetimes with a high relative change in the signal under
optical excitation, making them promising candidates for high-speed modulators.
Here, combination of SWCNTthin films and stretchable substrates facilitated
studies of the SWCNT mechanical properties under strain,and enabled the
development of a new type of an opto-mechanical modulator. By applying a
certain strain to the SWCNT films, the effective sheet conductance and
therefore modulation depth can be fine-tuned to optimize the designed
modulator. Modulators exhibited a photoconductivity change of 3-4 orders of
magnitude under the strain due to the structural modification in the SWCNT
network. Stretching was used to control the THz signal with a modulation depth
of around 100 % without strain and 65 % at a high strainoperation of 40 %. The
sensitivity of modulators to beam polarisation is also shown, which might also
come in handy for the design of a stretchable polariser. Our results give a
fundamental grounding for the design of high-sensitivity stretchable devices
based on SWCNT films.
