如何使用php curl而不是header('Location:)返回令牌?

这是有效的代码:

if (!isset($_GET['code'])) {
// If there is no token, this returns the token with the 'code' parameter
$url = "https://start.exactonline.co.uk/api/oauth2/auth";
$params = array(
    "response_type" => "code",
    "client_id" => $clientId,
    "redirect_uri" => $redirectUri
    );
$request_to = $url . '?' . http_build_query($params);
header("Location: " . $request_to);
die('Redirect');
}

我试过了,但没有成功:

$curlOpt = array();
$curlOpt[CURLOPT_URL] = 'https://start.exactonline.co.uk/api/oauth2/auth?client_id=XXXXXXXXX&redirect_uri=ZZZZZZZZ';
$curlOpt[CURLOPT_RETURNTRANSFER] = FALSE;
$curlOpt[CURLOPT_SSL_VERIFYPEER] = FALSE;
$curlOpt[CURLOPT_FOLLOWLOCATION] = TRUE;
$curlOpt[CURLOPT_POSTFIELDS] = array(
    'response_type' => 'code');
$curlHandle = curl_init();
curl_setopt_array($curlHandle, $curlOpt);
curl_exec($curlHandle);

我怀疑我的CURL请求是不正确的,但我不知道如何修复它,任何帮助将不胜感激。