Since the Vf vs If plot supplied by Cree is really tailored to the higher end of the current range, I decide to measure it at currents relevant to use in cathode biasing. I set up a simple test rig using a AA battery (1.61V measured) and a series of resistors on the + leg of the circuit, to deliver a range of currents to the diode, then measured the voltage across the diode for each current.
The chart above shows the results for the current range of 2.79mA to 65.8mA. Dynamic resistance looks to be fairly low in this range, if not perfectly linear.
