Among the several fiber optic components used in fiber optic communication systems and in fiber optic sensors is the fiber grating. Fiber Grating sensors have emerged as potential sensing platforms for structural health monitoring, bio-sensing applications and harsh environment applications. Fiber Grating sensors are broadly classified into Fiber Bragg Grating sensors and Long Period Grating sensors. Generally, these sensors offer higher accuracy, longer stability, smaller size, immunity to electromagnetic interference (EMI) and the ability to measure ultra-high speed events and thus they surpass traditional electrical and mechanical sensors. These sensors owing to convenience of multiplexing in wavelength domain enable distributed sensing where multiple sensors are monitored by a single signal processor bringing cost-effectiveness. Development of FBG sensors for vibration measurement and crack identification has been carried out in CSIO. In the area of bio-sensing, Glucose oxidase (GOD) immobilized long period grating (LPG) fibers for the specific and sensitive detection of glucose have been proposed and experimentally demonstrated. Proposed technique can further be extended to develop LPG fiber based novel, sensitive and label free nanosensors for disease diagnosis and clinical analysis which will help to address social issues like adulteration, pathogen and pesticide detection in food and beverages.