mymodule.info

name = MyModule
description = My Module
core = 7.x
package = MyModule
php = 5.2.4
dependencies[] = views
files[] = mymodule_handler_filter_fulltext.inc

mymodule.views.inc

<?php
/**
 * Implements hook_views_data_alter().
 */
function mymodule_views_data_alter(&$data) {
  // Adds direct parse mode views fulltext filter to the Default Node Index.
  $data['search_api_index_default_node_index']['mymodule_views_fulltext'] = array(
    'group' => t('Search'),
    'title' => t('Fulltext search using Solr/Lucene syntax'),
    'help' => t('Search several or all fulltext fields using direct Solr/Lucene syntax.'),
    'filter' => array(
      'handler' => 'MyModuleViewsHandlerFilterFulltext',
    ),
  );
}

mymodule_handler_filter_fulltext.inc

<?php
/**
 * @file
 * Views Search API fulltext field handler that supports direct searches.
 *
 * Note that the tokenizer processor must be disabled.
 */

class MyModuleViewsHandlerFilterFulltext extends SearchApiViewsHandlerFilterFulltext {
  /**
   * Add this filter to the query.
   */
  public function query() {
    // Set parse mode to direct so the search input is sent directly to Solr.
    $this->query->setOption('parse mode', 'direct');
    parent::query();
  }
}