Equalization of Square Pulse in Visible Light Communication
As shown (with no output load) the signal at Vout will not be affected much at all by your RC "equalizer".  If you were to place a low value resistive load (maybe 100 ohms or lower) from Vout to ground you should then see a better response.  If the added load doesn't give a satisfactory square wave then you might even consider placing a simple high speed comparator circuit after the AD8010.  To limit the frequency response of the AD8010 (and reduce oscillations etc.) also consider placing a very small value capacitor across the 10k, (low pf range).  The added capacitor would help to give a smooth pulse to the comparator,(if used), then the comparator can further square up the signal.  In addition be sure to use bypass capacitors at all power pins.