Highly efficient acoustooptic tunable filter based on cladding etched single-mode fiber

The efficiency enhancement of an acoustooptic tunable filter on cladding etched single-mode fiber (SMF) is investigated experimentally. When the fiber diameter is etched down to 30 μm, the acoustooptic coupling efficiency from the LP/sub 01/ core mode to the LP/sub 11/ cladding mode was increased by an order of magnitude, and the RF power consumption was reduced by two orders of magnitude. A highly efficient 8-cm-long 25-μm-thick AOTF on cladding etched SMF with an insertion loss of <0.2 dB, and RF power as low as 1.1 mW was demonstrated.