All-fiber acoustooptic phase modulators using chemical vapor deposition zinc oxide films

For the first time we report an all-fiber acoustooptic phase modulator using a zinc oxide (ZnO) film deposited by modified single source chemical vapor deposition. This technique allows deposition over the full 360° fiber surface without the need for sample rotation, greatly simplifying the manufacturing process. The maximum phase shift measured for our 6 mm long devices was 3.5 rads for a drive power of 580 mW. Unlike devices fabricated using sputtered ZnO films the maximum attainable phase shift is not significantly limited by thermal and mechanical loss effects at higher driving powers which we attribute to the excellent chemical composition of our chemical vapor deposition (CVD) grown films. A maximum efficiency of 0.28 rad/√(mW)/cm of device length was measured which may be attributed to the relatively thin films used in this experiment (0.4-0.9 μm)