It's possible. In your "Widget.js" file use the "jimu/loaderplugins/jquery-loader":
define(['dojo/_base/declare', 'jimu/BaseWidget', 'jimu/loaderplugins/jquery-loader!https://code.jquery.com/jquery-1.11.2.min.js'],
function(declare, BaseWidget, $) {
return declare(BaseWidget, {
...
}
}