In this paper it is proposed and designed an alloptical Sampler (o-Sampler) intended to be part of future optical Digitising Radio-over-Fibre (o-DRoF) transceivers. It is based on the Semiconductor Laser Amplifier Loop Mirror (SLALOM) configuration thus using the nonlinearities of a semiconductor optical amplifier (SOA) in cross-switching regime. The proof-ofprinciple is established by computer simulations using 500 MHz analogue signal and 2.5 GS/s sampling pulses both in the C-band. The proposed o-Sampler outputs real-time generated optical samples from an analogue RoF signal. The simulated device is rather compact, polarisation independent, potentially optically integrable and requires few mW of sampling peak power.