How to avoid using "I" in a research paper in case of referring to my previous work?
There are two options I know of (I've seen both). 

One is to ignore that the person you are referring to is one of the authors, and write exactly the same way as if they were a third party. I guess this makes some sort of sense if there is no direct link between the two sets of work.

The other option is to use 'the first author' (or 'the second author', as applicable).