Figure 4

Secure key bit rate data bandwidth dependence.

Experimental secure bit rate as a function of data bandwidth simulated by increasing the launch power of 10 data lasers. Experimental secure bit rate using a 100 GHz filter in the quantum receiver (blue circles), extending the results reported in the inset of Fig. 3. Experimental secure bit rate data using a 25 GHz filter in the quantum receiver (red circles). Blue and red triangles are the corresponding QBERs for both experiments. Solid and dashed lines are results from numerical simulations. Also shown are secure bit rate numerical simulations using a 25 GHz filter in the quantum receiver for fibre distances of 25 km and 75 km (grey lines).