PHP encoding an array or arrays into JSON for JS Slideshow plugin.

PHP - WordPress - JSON encode

    function get_pop_up($ID) {

        $rows_fss = get_field('slideshow_repeater',$ID);

        $output = "";

        if($rows_fss) {

            $output .= "<div id='inline1' style='display: none;'>";

                $output .= "<div data-src='";


                            $images_array = array();

                            foreach($rows_fss as $row_fss) {

                                    $image_attributes   = wp_get_attachment_image_src( $row_fss['slide_photo'], 'large' );

                                    array_push($images_array, 
                                        array(
                                            "src" => $image_attributes[0], 
                                            "wid" => $image_attributes[1], 
                                            "hei" => $image_attributes[2],
                                            "cap" => htmlspecialchars($row_fss['slide_title'], ENT_QUOTES)
                                        )
                                    );

                            }

                            $output .= json_encode($images_array);


                $output .= "
                        '></div>";

            $output .="</div>";

        }

        return $output;

    }