If you would like to authorize travel for an employee or anybody else, here is a sample template you can use to write a travel authorization letter.
Subject: Authorization letter to permit travel.
Please be informed that we authorize you to travel to [Name of Place]. Kindly go through the travel details and confirm the same at the earliest.
Travel Date: [Mention the Date to travel]
Travel From/To: [Mention the city of departure]/ [Mention the city of arrival]
Mode of Travel: [Mention the mode, along with its details]
Purpose: [Mention the purpose of travel]
If you have any questions concerning this letter, please contact [e-mail or phone number]