This is something I have been wanting to do a while and bought the material quite some time ago do a project using quantum dots but those will have to wait. I have been wanting to encapsulate my own LEDs to do experiments on what the absolute best setup is for my aspheric setup. I have not had time yet to run any tests but I got some pictures today and thought I'd get it started. I am using a high grade optical silicone meant for encapsulating LEDs. This is not Home Depo material here. I removed the domes of both LEDs and scraped off the silicone gel down to the silicone layer that holds the phosphor.
From left to right we have an XR-E with an acrylic optic applied over the encapsulant, a regular XR-E, and an XR-E with only silicone encapsulant. Notice how you can already see the LED die on the one with the acrylic optic.
See the change in die size?
I'll have to get to the tests at a later date.