To convert PDF Documents to Word format.

$wordOutputOptions = new WordOutputOptions();

// Optionally convert only the first page
$wordOutputOptions->SetPages(1, 1);

// Requires the Structured Output module
Convert::ToWord($filename, $output_filename, wordOutputOptions);

To convert PDF Documents to Excel format.

$excelOutputOptions = new ExcelOutputOptions();

// Optionally convert only the first page
$excelOutputOptions->SetPages(1, 1);

// Requires the Structured Output module
Convert::ToExcel($filename, $output_filename, excelOutputOptions);

To convert PDF Documents to PowerPoint format.

$powerPointOutputOptions = new PowerPointOutputOptions();

// Optionally convert only the first page
$powerPointOutputOptions->SetPages(1, 1);

// Requires the Structured Output module
Convert::ToPowerPoint($filename, $output_filename, powerPointOutputOptions);

Convert PDF to Office
Full sample code which shows how to convert generic PDF documents to Word, Excel, PowerPoint format