How to handle application authentication popup in Safari browser

I have tried robot class to handle authentication popup in safari browser. but I am facing expected url launching but authentication credentials not getting accept.

driver.get(url);
driver.switchTo().alert();
Robot rb = new Robot();

//Enter user name by ctrl-v
StringSelection username = new StringSelection(username);
Toolkit.getDefaultToolkit().getSystemClipboard().setContents(username, null);            
rb.keyPress(KeyEvent.VK_CONTROL);
rb.keyPress(KeyEvent.VK_V);
rb.keyRelease(KeyEvent.VK_V);
rb.keyRelease(KeyEvent.VK_CONTROL);

//tab to password entry field
rb.keyPress(KeyEvent.VK_TAB);
rb.keyRelease(KeyEvent.VK_TAB);
Thread.sleep(2000);

//Enter password by ctrl-v
StringSelection pwd = new StringSelection(pwd);
Toolkit.getDefaultToolkit().getSystemClipboard().setContents(pwd, null);
rb.keyPress(KeyEvent.VK_CONTROL);
rb.keyPress(KeyEvent.VK_V);
rb.keyRelease(KeyEvent.VK_V);
rb.keyRelease(KeyEvent.VK_CONTROL);

//press enter
rb.keyPress(KeyEvent.VK_ENTER);
rb.keyRelease(KeyEvent.VK_ENTER);

//wait
Thread.sleep(5000);

String text=driver.getTitle();
System.out.println(text);
driver.close();