A Micro-Opto-Mechanical-System (MOMS) based technology for the fabrication of Fabry-Perot interferometers on optical fiber is presented. Exploiting silicon micromachining techniques, the fabrication of ultrasonic receiver arrays suitable for wideband and high performance applications is demonstrated. Thanks to their high miniaturization level, the devices presented may be suited to minimally invasive endoscopic applications in medicine. The devices are based on the use of a SU-8 polymer interferometer manufactured on a micromachined silicon frame whose thickness can be modulated by the incoming ultrasound waves. In this way, the ultrasonic detection is performed by measuring the Fabry-Perot thickness modulation from the variation of the reflected intensity of a fiber-driven continuous laser beam hitting the interferometer.