A Compact All-Fiber LPG-AOTF Frequency Shifter on Single-Mode Fiber and Its Application to Vibration Measurement

We demonstrate a compact, all-fiber frequency shifter by cascading a CO
₂
-written long-period grating with a flexural acoustic-wave-induced microbending grating on a single-mode fiber. Carrier and image sideband suppressions of 30.0 and 28.1 dB, respectively, are measured. An all-fiber vibrometer based on this frequency shifter capable of nanometer resolution at frequencies up to megahertz is also demonstrated.