Whispering Gallery modes (WGMs) in optics are the eigen modes of circular cavities (like microspheres, microdisks, etc.) which get excited when a light beam gets trapped due to continuous total internal reflections and after orbiting the cavity, it returns to its starting point in phase. Due to their high Quality factor and confinement of enhanced field in very small mode volume, such systems are ideally suited for bio-chemical sensing, non- linear optics and cavity QED experiments. These modes can be efficiently and selectively excited using evanescent field of micro-fibers. I will discuss the development of set ups for fabrication of micro-sphere cavities and tapered fibers with micron and sub-micron waist sizes. Experimental techniques and set up for exciting WGMs in micro-spheres using taperd fibers will also be discussed. I will present the observations of WGMs in silica micro-spheres and briefly discuss our planned experiments on time-dependent microsphere cavities (i.e. liquid drops) and metal coated microspheres.
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