Abstract
Non-reciprocal phase shifters have been attracting a great deal of attention due to their important applications in filtering, isolation, modulation, and mode locking. Here, we demonstrate a non-reciprocal acoustic phase shifter using a simple acoustic waveguide. We show, both analytically and numerically, that when the fluid within the waveguide is biased by a time-independent velocity, the sound waves travelling in forward and backward directions experience different amounts of phase shifts. We further show that the differential phase shift between the forward and backward waves can be conveniently adjusted by changing the imparted bias velocity. Setting the corresponding differential phase shift to 180 degrees, we then realize an acoustic gyrator, which is of paramount importance not only for the network realization of two port components, but also as the building block for the construction of different non-reciprocal devices like isolators and circulators.
Highlights
Microwave phase shifters are two-port components that provide an arbitrary and variable transmission phase angle with low insertion loss [1–3]
Various types of microwave phase shifters have been proposed and demonstrated over years, all of which can be fundamentally categorized into two groups: reciprocal and non-reciprocal phase shifters
Non-reciprocal phase shifters providing different phase shift for forward and backward waves, are of more importance especially when it comes to the realization of devices like gyrators [18], isolators [19], and circulators [20], being critical for radar systems and networks
Summary
Microwave phase shifters are two-port components that provide an arbitrary and variable transmission phase angle with low insertion loss [1–3]. [22], itbreak was shown that applying a time-independent bias velocity to waves stationary fluids allows one to In strongly the time reversal symmetry and to induce acoustic to stationary fluids allows one to strongly break the time reversal symmetry and to induce acoustic non-reciprocity This salient feature was leveraged to demonstrate a subwavelength circulator in non-reciprocity. By fluid bias velocity that corresponds to a differential shift degrees, implement an setting acoustica gyrator, which is an important two port componentphase serving as of the[180] building we for implement gyrator, whichdevices is an important two port component as the block a large varietyan of acoustic non-reciprocal acoustic such as isolators and circulators.serving. We believe that our finding opens up exciting frontiers in the field of modern acoustic engineering that our finding opens up exciting frontiers in the field of modern acoustic engineering [34–67] for the design and realization of various innovative components, such as phase modulators, beam forming devices, switches, and frequency convertors
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