If your Outlook calendar is using Gmail, you can share it with other people even if they aren't part of your company.
First log into Google on your web browser, and then open the Google Calendar. You'll see the Google Calendar app in the Applications menu:
With your calendar open, hover your mouse over your calendar name on the left sidebar, and select "Share this Calendar".
You'll see a place where you can enter email addresses of the people you want to share your calendar with. Enter their email addresses and they'll get a link in their inbox, that lets them access your calendar.