Nonreciprocal conversion is essential for protecting sources and enabling unidirectional signal routing in photonic, phononic, electronic, and quantum systems, yet conventional implementations often rely on magnetic bias that can be difficult to integrate on chip. We propose a magnet-free scheme for frequency-domain nonreciprocity based on sequential, time-gated modulation in a three-mode system. By activating interactions in a fixed temporal order, the forward and reverse frequency-conversion pathways acquire unequal dwell times in a lossy intermediate mode, producing strong nonreciprocity without requiring nonlinearities or magnetic materials. Using harmonic-balance and Dyson-Born expansions, we derive an analytical expression for the isolation ratio and show that breaking time-reversal symmetry alone is insufficient to produce isolation in this scheme: Dissipation in the intermediate mode is necessary, and the isolation is maximized at a finite loss. The resulting framework identifies how duty cycles, modulation frequency, relative delay, coupling strength, and loss control the isolation, in agreement with direct time-domain simulations. The approach is general and applicable to integrated photonic, phononic, microwave, and superconducting-circuit platforms.

Close

PrevNext

View figure in article

• Cavity quantum electrodynamics
• Non-reciprocal transmission
• Phononics
• Micromechanical devices
• Cavity resonators