Microsoft OCR API with PHP

I am fairly new to PHP and I am trying to use the Microsoft OCR API. I already have my key and it is working as I have tested here: https://brazilsouth.dev.cognitive.microsoft.com/docs/services/unified-vision-apis-public-preview-2023-04-01-preview/operations/61d65934cd35050c20f73ab6/console.

So what I am trying to do is make a PHP API request. I cannot install any libraries to do this as it is a requirement for what I am doing. So I am trying to use the CURL and because of my newbieness in PHP don´t know if this is the best approach nor whats wrong with it.

The request the above mentioned webpage is as follow:

Here is the code that I have:

<?php
class Computer_Vision{

    public function __construct(){          
        $this->azure_ocr="https://brazilsouth.api.cognitive.microsoft.com/computervision/imageanalysis:analyze?api-version=2023-04-01-preview&features=read&language=pt HTTP/1.1";
        $this->subscription_key="blahblahblah";
    }
    
    public function recognize($image_url){

        $data = array("url" => $image_url);
        
        $azure_url = $this->azure_ocr;
        print($azure_url . "<br/>");
        
        $key=$this->subscription_key;
        $data_string = json_encode($data);
        print($data_string . "<br/>");
        
        $curl = curl_init($azure_url);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $data_string);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1 );
        curl_setopt($curl, CURLOPT_POST,           1 );
        curl_setopt($curl, CURLOPT_HTTPHEADER, array(
            'Content-Type: application/json',
            'Ocp-Apim-Subscription-Key:'.$key
        ));
        $response = curl_exec($curl);
        print("response: " . $response . "<br/>");
        
        
        if(curl_error($curl)) {
            print('error:' . curl_error($curl));
        } else {
            $json_object = json_decode($response, true);
            print("json_object: " . $json_object);
        }
        
        curl_close($curl);
    }
}
?>

on my index.php I have:

<?php 
    $azure = new Computer_Vision();
    $image_url = "https://portal.vision.cognitive.azure.com/dist/assets/OCR1-6dda571d.jpg";
    $ocr = $azure->recognize($image_url, "ocr");
?>

the code above doesn´t give me any errors (at least it does not enter the curl_error condition) but it gives me an empty response

what would be the best way to do this? what I am doing wrong? any help is more than appreciated .