I see that several people have asked this question, but to me, it doesn't make any sense.
When you build an application with Angular, you are building a Single Page Application. That inherently means "one browser window".
What would the expected behavior be if you clicked on a router link, which, by definition, replaces the current component with a new one, if the new component were rendered in a new window?
What you would actually get is a second instance of the application.
I suggest that you either use Angular in the way that it was meant to be used, as an SPA app, or look into using a different framework.
That said, if what you are trying to do is open non-Angular content in a new window (a different site, or something that's served directly by your back-end (e.g. A PDF or a spreadsheet), then just use an anchor tag with an href attribute, instead of a routerLink.