how to call popup window while ajax callback post method

Question

1) my call back function

function fetch_servicedata1() {
  
    var filename = document.getElementById("ctl00_ContentMain_hdnfile").value;
    companyID = document.getElementById('ctl00_ContentMain_hdnCompanyID').value;
    var service_Res = "";
    $.ajax({
        type: "POST",
        url: "UtilityService.asmx/New_FatchCacheXMLString",
        data: "filename=" + filename + "&CompanyID=" + companyID+"&Rq_CID=1",
        dataType: "xml",
       // cache: false,
        async: true,
        success: function (xml) {
            // alert('first relsut');
         
            if (xml.documentElement.text) {
                fnFetchResult_New(xml.documentElement.text);
            }
            else {
                fnFetchResult_New(xml.documentElement.textContent);
            }
            if(TotalResultCount>0)
                document.getElementById("divProgressBar").style.display = '';
            secondPagingFlag = true;
            console.log('before func 2');
            
           // setTimeout(fetch_servicedata2(), 1);
          },
        error: function (xhr, ajaxOptions, thrownError) {
        //    alert(xhr.status);
         //   alert(thrownError);
          //  $('#waitScreen').css('display', 'none'); $('#waitBox').css('display', 'none');
        }
    });
}

2) my event

$(".external-link").live("click", function (e) {

$.ajax({
type: "GET",
async: true,
url: "",
success: function () {
window.open("HtlIntermediate.aspx");
}
})
});

i need to event call without wait for call back success i have called call back function and it will take around 1 minute to response and in the meantime need to click on the button and open popup window which show data from database using asp.net