Ultrasound transmitters are widely used in various applications such as medical imaging and structural health monitoring.Most recently, traditional ultrasound transmitters are facing challenges in meeting design specifications such as broad bandwidth and compact size, which are essential for many applications.In order to overcome these challenges, novel ultrasound transmitters based on the photoacoustic principle as well as optical fibers, have been developed by various researchers.The photoacoustic principle is an optical ultrasound generation mechanism which involves optical energy absorption and conversion.In this paper, the history of the photoacoustic principle is reviewed and the efficiency of photoacoustic conversion is discussed.This paper focuses on fiber optic ultrasound transmitters which utilize the photoacoustic principle on optical fibers to generate ultrasound.In addition, various applications are discussed in this paper and the unique advantages of fiber optic ultrasound transmitters are covered.