Broadband THz Switching with Extremely Low Insertion Loss and Superior Isolation

Dynamically tuning and reconfiguring microwave bandpass filters using optical control of switching elements

“…As a result, the proposed filter design can be easily scaled up for mmW‐THz operation without extensive structural modifications. In addition, as demonstrated in Shi et al, 11 and Li et al 12 THz switches using the proposed mechanism show superior RF performance as compared to most THz switches using different technologies. Finally, it is worth noting that the demonstrated switching approach can exploit spatial optical modulation and operation using computer‐programmed light patterns without any extra biasing circuits, making it suitable for large‐scale switch array or network applications, enabling the development of more advanced and complex THz/microwave filters (e.g., the filter banks in Figure 1) with a large number of switching elements.…”

“…In addition, switching elements using Ge as the active layer can be employed for even higher achievable photoconductivity since Ge offers a higher carrier lifetime (i.e., 1 ms) and light absorption coefficient (i.e., 5.03 × 10 5 cm −1 ) when compared to Si (with only 1 μs and 6.7 × 10 3 cm −1 , respectively). Finally, fully integrated switching elements using a noncontact configuration for eliminating the rapid carrier recombination at the contacts as described in Shi et al, 11 and Li et al 12 can be adopted for optimized both device and filter performance. The power consumption of the proposed switching approach could be significantly reduced by integrating ferroelectric (FE) latching for nonvolatile operation 12,26 …”

“…Finally, fully integrated switching elements using a noncontact configuration for eliminating the rapid carrier recombination at the contacts as described in Shi et al, 11 and Li et al 12 can be adopted for optimized both device and filter performance. The power consumption of the proposed switching approach could be significantly reduced by integrating ferroelectric (FE) latching for nonvolatile operation 12,26 …”

“…The power consumption of the proposed switching approach could be significantly reduced by integrating ferroelectric (FE) latching for nonvolatile operation. 12,26 Another key consideration for dynamically tuning and reconfiguring BPFs is the operation speed. The operation speed of the proposed BPF is primarily determined by the carrier lifetime inside the active layer (i.e., Si or Ge) of the switching elements employed.…”

“…10 To address these challenges and develop an alternative approach for achieving high-performance multifunctional filter circuits required in next-generation communication systems, a novel optical switching technology based on the modulation of semiconductor photoconductivities has been introduced and explored. 11 This switching technology, previously validated in both D-band and G-band (110-220 GHz) using silicon, 12 has been successfully employed to demonstrate a versatile and adaptable bandstop filter (BSF) using split-ring resonators (SRRs) 13 in the absorption mode. To further unlock the technology potential, demonstrate the design flexibility, and attain dynamic tunability for various applications, in this paper, we propose and demonstrate a prototype single band tunable and reconfigurable BPF element (see channel 1 in Figure 1B) based on transmission-mode SRRs as an approach for achieving more complex switched filter banks as depicted in Figure 1.…”