How can portlet call servlet and servlet redirect to jsp ?

[Vivek Srivastava, modificado hace 12 años.]

I want to open a popup window from my portlet to authenticate user for authenticating and returning back to portlet once authentication done.

So to achieve this I have created a servlet for authenticating user, which I am calling from the portlet.
popup window can be a jsp page.
so portlet ->servlet works but when trying to redirect to jsp it won't come as a popup window nothing shown no error message either