Translatorの利用方法-Azure

<?php
    $get_param = "api-version=3.0&to=en&textType=html";
    $url = "https://api.cognitive.microsofttranslator.com/translate?" . $get_param;

    $region = "japaneast";
    $key = "xxxxxxxxxxxxxxxxxxxx";
    $header = array(
        "Content-Type: application/json",
        "Ocp-Apim-Subscription-Region: " . $region,
        "Ocp-Apim-Subscription-Key: " . $key
    );

    $text = "こんにちは、世界!";
    $param = array(
        array(
            "Text" => $text
        )
    );
    $param = json_encode($param);

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_URL, $url); 
    curl_setopt($ch, CURLOPT_HEADER, true);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $header); 
    curl_setopt($ch, CURLOPT_POSTFIELDS, $param);

    $result = curl_exec($ch);

    curl_close($ch);