Optical sensors that can be used in harsh environments are desirable in a wide range of industrial and military applications where conventional measurement devices are difficult to apply due to the harsh environments. Optical fiber sensors have been demonstrated to be attractive for the measurement of a wide variety of physical parameters because of such inherent advantages as 1) small size, 2) an immunity to electromagnetic interference, 3) high resolution, 4) non-electrically conducting, 5) capability of responding to a wide variety of measurands, 6) avoidance of electric sparks, 7) resistance to harsh environment, 8) remote operation, and 9) capability of multiplexing. In the past two decades, fiber sensors have been demonstrated and developed. The optical sensor research at the Virginia Tech Center for Photonics Technology (VTCPT) has been mainly focused on the development of sensors for measurement of pressure, temperature, strain, acoustic waves, flow, electric partial discharges, surface mapping and 3-D temperature imaging. Most of these sensors are based on optical fibers, including silica glass fiber with various polymer and metallic coatings and single-crystal sapphire fiber waveguides. In terms of the optical parameters being modulated, these sensors could be approximately classified into interferometric, polarimetric, intensity-based, and wavelength-coded devices. This paper presents several examples of the sensors recently developed at Virginia Tech.