Nonreciprocal devices having reconfigurable nonreciprocal transfer functions through nonreciprocal coupling

A system comprising:

• a waveguide through which waves at a first frequency propagate with a first wavevector and with a second wavevector in a direction opposite to the first wavevector;
• a frequency-dependent device that operates within a frequency range and modifies the waves through the waveguide in a way that is dependent on the first frequency;
• a set of couplers to couple the waveguide to the frequency-dependent device at spatially separated coupling sites, the set of couplers comprising at least a first coupler and a second coupler;
• and
• a signal processor coupled to the set of couplers, the signal processor to:
• generate a sinusoidal signal;
• generate a first modulated coupling constant via modulation of a first coupling constant, of the first coupler, using the sinusoidal signal;
• generate a second modulated coupling constant via modulation of a second coupling constant, of the second coupler, using the sinusoidal signal;
• and
• apply a phase offset of the second modulated coupling constant as compared to the first modulated coupling constant, to induce nonreciprocal coupling, with respect to the frequency-dependent device, of the first wavevector compared to the second wavevector.

A method comprising:

• coupling, using a set of couplers, a waveguide to a frequency-dependent device, wherein waves at a first frequency propagate in the waveguide with a first wavevector and with a second wavevector in a direction opposite to the first wavevector, and wherein the frequency-dependent device operates within a frequency range;
• modifying, with the frequency-dependent device, the waves within the waveguide in a way that is dependent on the first frequency;
• and
• inducing, via modulation of coupling rates of the set of couplers, nonreciprocal coupling, with respect to the frequency-dependent device, of the first wavevector compared to the second wavevector.