Frequency shifter based on the well-knownacousto-optic effect is realized in an all-fiber form resulting in low losswithout sensitive mechanical alignment. Light traveling in a two-mode fiberinteracts with a traveling acoustic wave along the fiber to be coupled to thesecond mode with a frequency shift. The frequency shifted light is then coupledto a single-mode fiber using a mode-selective coupler.
•Negligible loss
•Frequencyshift of 0.5 – 3 MHz
•All-fiberconstruction: no free space light path
•Switchingtime of 20-50 microseconds
•Heterodyneinterferometry
•Opticalswitching