Double passage acousto-optical filter with polarisation conversion regions

摘要

A double-passage acousto-optical device 10 through which light passes twice comprising an input optical fiber 3, by which optical radiation is introduced from an external source connected to a first input port 202 of an acousto-optical switch 8. The switch 8 is connected to a radio-frequency generator. A first output port 205 of the acousto-optical switch 8 is connected to an optical isolator 7, whose output is optically connected to a polarization controller 9. The output of the polarization controller is coupled to a second input port 203 of the acousto-optical switch 8. A second output port 204 is coupled to an output fiber 2 of the acousto-optical device 10. The acousto-optical switch 8 within device 10 is a 2x2 filter that is selective in respect of wavelength and has a response independent of polarization. The switch 8 can be used to select optical signals between the two inputs.