The Libraries' plotter is in guest services, not the FabLab, but all the same - the Canon iPF8400 plotter we have also has a max resolution of 1200 dpi
I've not personally needed to look for printing at a higher resolution than this, though there may be some commercial printers in the area who have extremely high resolution printers. Generally, 300dpi is a high-res print and 1200 dpi is ultra high-res beyond what is often used even for extremely detailed fine art applications.
The dot size of a 1200 dpi print should be about 20 microns; if you are looking to print with micron resolution, I would suggest getting in touch with some people in the NanoFab department on campus, as they would be more likely to have dealt with similar technical hurdles in their research.
good luck!!
