Demonstration of 1×4 port optical fibre switch using electric field-controlled dynamic offset coupling and modelling

We experimentally demonstrate a 1×4 single-mode fibre (SMF) switch using electric field-controlled direct fibre-to-fibre offset-coupling. The switch functions through cantilever-deflection of signal carrying input optical fibre to couple power into the designated fibre port. The freely suspended end of the cantilever-fibre is selectively coated with an electrostrictive-nanocomposites and the off-set coupling is precisely actuated by controlled interaction between the applied electric field and electrostrictive transducer. Through a series of experiments, we minimized misalignment-loss and fine-tuned the coupling performance, achieving a measured insertion-loss of 0.7–0.95 dB, crosstalk of −48 dB, switching time of 7 ms, and driving power of 120 mW. Switch underwent alternate-day testing, 1000 cycles/day for 30 days, without performance degradation. Modelling the varying free-space coupling geometry showed good agreement with experimental data, validating the demonstration. Being wavelength-independent and almost insensitive to input polarization, the switch is ideal for port multiplexing in fibre networks and smart sensor circuits.