KW CULNM1.TG is 4.0x4.0mm version of KW CSLNM1.TG (or 1mm2 version of Oslon boost HX), with lower thermal resistance, I tested two 5Q bin samples under same conditions (fan cooled heatsink), results:
So we got the first white LED that broke 1000lm/mm2 barrier (by a decent margin in case of higher performing sample)
What can be seen from numbers is two samples are within 5Q bin rating (710 - 800lm@3A), but one is at bottom and other is closer to upper level. 5Q bin is comparable to 6N bin of CSLNM1.TG (315-355lm at 1A).
Compared to CSLNM1.TG (white flat) peak current is just a litlle bit higher 6.0-6.5A vs ~5.75A. I was surprised by this, I expected more like 7A, but it seems droop effect at these current densities becomes so dominant that output stops increasing even if you cool LED die well.
But CULNM1.TG's lower thermal resistance does help and max. output is higher at high currents.
Also the other good thing about lower thermal resistance is lower junction temperature, at 6Amps die temperature is about 75C higher than ambient, CSLNM1.TG temperature at 6Amps would be ~96C higher than ambient. So CULNM1.TG should be more reliable /longer living at high currents.
Disadvantage is considerably higher price compared to CSLNM1.TG and the fact that it has been already "scheduled for obsolescence " by OSRAM due to lower than expected demand.