  We present a wearable device with III-V nanowires in a flexible polymer,
which is used for active mechanical tuning of the second-harmonic generation
intensity. An array of vertical GaAs nanowires was grown with metalorganic
vapour-phase epitaxy, then embedded in polydimethylsiloxane and detached from
the rigid substrate with mechanical peel off. Experimental results show a
tunability of the second-harmonic generation intensity by a factor of two for
30% stretching which matches the simulations including the distribution of
sizes. We studied the impact of different parameters on the band dispersion and
tunability of the second-harmonic generation, such as the pitch, the length,
and the diameter. We predict at least three orders of magnitude active
mechanical tuning of the nonlinear signal intensity for nanowire arrays. The
flexibility of the array together with the resonant wavelength engineering make
such structures perspective platforms for future bendable or stretchable
nanophotonic devices as light sources or sensors.
