php로 몽고디비 조회할시 대소문자 구분업시 하는거를 적용하려는데 어떻게하면될까요??

<?php

$model_code = $_GET['model_code'];

// required headers

header("Access-Control-Allow-Origin: *");

header("Content-Type: application/json; charset=UTF-8");

// include database file

include_once 'mongodb_config.php';

$dbname = 'product';

$collection = 'product';

//DB connection

$db = new DbManager();

$conn = $db->getConnection();

// read all records

$filter = ['model_code' => $model_code];

$option = [];

$read = new MongoDB\Driver\Query($filter, $option);

//fetch records

$records = $conn->executeQuery("$dbname.$collection", $read);

echo json_encode(iterator_to_array($records), JSON_UNESCAPED_UNICODE);

?>