You can use the Blackberry Desktop Redirector as one choice. Installing it
will depend upon your type of account and whether or not you have
administrative access to your laptop.
The Desktop Redirector may redirect all your mail to your Blackberry as well
however. I can't recall if you can choose to synch just your Calendar. Mail
still goes to Outlook and leaves a copy there, but a copy is also redirected
to your Blackberry. I believe you also have to leave you laptop on and logged
in (you can lock it) for the Redirector to run.
I haven't used the Redirector in several years which also means if there's a
new method of doing it, I may not be aware.
You may also be able to do this via your Blackberry provider but I don't
know if they can exclude everything but your calendar. You can check their
website to make sure or call their Technical Support.
If you're using Outlook at work using an Exchange account, if there are
other Blackberry users you may consider talking to your IT staff to see if
they have a BES they can add your Blackberry to (unless this is a personal
Blackberry and not work-related).