Brief history about the optical fibers is presented. The different types of optical fiber sensors are highlighted... The sensors are specifically designed for measurement of various Physical and Chemical parameters. The work covers following aspects of optical fiber sensor:_ The effect of bend radius with respect to temperature in single mode communication fiber and polarisation maintaining fiber._ A simple and cost effective intensity modulated method for the micro displacement sensor. _ Analysis of Cu (II) presence in water based on Evanescent wave absorption technique._ A simple and cost effective method of measurement of ethanol concentration in water using Fiber Bragg Grating.