In this paper, the transmission characteristics of unetched and etched single mode fibers with acoustic wave input is investigated where the cladding layer of a single mode fibre is reduced. In other part transmission characteristics of high birefringence (Hi-Bi) fiber loop mirrors with etched and unetched fiber has also been demonstrated. In optical sensing, these devices may be used as strain and temperature sensors, in a separate or in a simultaneous measurement. In the end the two results have been compared.