* Multiple choice question-A,B,C or D * Air in the cladding yields a fiber with a _____ index step. A. unpredictable B. zero C. small D. large A. unpredictable B. zero C. small D. large Solution option D because Increasing the air-filling fraction in the cladding typically leads to multimode behavior. An elliptical core can create a highly birefringent fiber that is polarization maintaining..