Abstract
The arrayed waveguide grating (AWG) is a versatile and scalable passive photonic multiplexer that sees widespread usage. However, the necessity of a waveguide array engenders large device size, and gratings invariably commute finite power into undesired diffraction orders. Here, we demonstrate AWG-like functionality without a grating or waveguide array, yielding benefits to compactness, bandwidth, and efficiency. To this end, we exploit optical tunneling from a dielectric waveguide to an adjacent slab in order to realize a slab-confined frequency-scanning beam, which is manipulated using in-slab beamforming techniques that we have developed in order to separate distinct frequency bands. In this way, we devise an all-intrinsic-silicon integrated 4 × 1 frequency-division terahertz multiplexer, which is shown to support aggregate data rates up to 48 Gbit/s with an on–off-keying modulation scheme, operating in the vicinity of 350 GHz. Our investigation targets the terahertz range, to provide a critical missing building block for future high-volume wireless communications networks.
Highlights
The terahertz range holds potential for ultra-wideband wireless communications applications, including 6G and beyond, due to large and under-utilized spectral bandwidth [1,2,3,4]
Terahertz waves are progressively leaked from the waveguide to the slab, in a process known as optical tunneling [28]
A target focus is selected, as shown in Fig. 2(c), and the distance from the slab boundary to this point is progressively shortened in order to compensate the phase that is acquired as the wave propagates within the dielectric waveguide
Summary
The terahertz range holds potential for ultra-wideband wireless communications applications, including 6G and beyond, due to large and under-utilized spectral bandwidth [1,2,3,4]. The development of all-dielectric platforms for terahertz waves opens the door to established passive nanophotonic multiplexers, such as arrayed waveguide gratings (AWG) [19,20]. Devices of this sort employ a dielectric slab as a free-propagation region to which several waveguides may connect. We exploit the well-known phenomenon of optical tunneling in an entirely new way for gratingless in-slab beamforming, which commutes no power into undesired diffraction orders This yields an efficient 300 GHz band 4 × 1 frequency-division multiplexer with a footprint area of 26 × 20 λ2central ∼ 4 cm2—between three and four orders of magnitude smaller than a comparable AWG—and deploy it in a demonstration of terahertz communications. We present a triplexer and a diplexer to illustrate the generality and scalability of the concept
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
