Variable optical attenuator systems

An optical switch/variable attenuator comprising:

• a polarization separating sub-system;
• at least one switchable transmission diffraction grating;
• and,
• a polarization recombining sub-system;
• means for varying a diffraction efficiency of said at least one switchable transmission diffraction grating;
• said polarization separating sub-system being optically disposed to receive an input optical beam of arbitrary polarization and also being capable of separating the input optical beam into a first optical beam of a first polarization and a second optical beam of a second polarization, said second polarization being distinct from said first polarization, and emitting a first emitted optical beam of the first polarization and a second emitted optical beam of the first polarization, said emitted first and emitted second optical beams constituting an input channel of the first polarization;
• said at least one switchable transmission diffraction grating being optically disposed to receive the input channel and capable of providing at least one transmitted channel, the at least one transmitted channel comprising at least one transmitted optical beam of the first polarization and at least one other transmitted optical beam of the first polarization;
• said at least one switchable transmission diffraction grating constituting a set of switchable transmission diffraction gratings;
• and,
• said polarization recombining sub-system being optically disposed to receive the at least one transmitted optical beam of the first polarization and the at least one other transmitted optical beam of the first polarization and capable of recombining the at least one transmitted optical beam of the first polarization and the at least one other transmitted optical beam of the first polarization into at least one final output beam;
• said at least one final output beam constituting a set of output beams.