Integrable microwave filter based on a photonic crystal delay line
The availability of a tunable delay line with a chip-size footprint is a crucial step towards the full implementation of integrated microwave photonic signal processors. Achieving a large and tunable group delay on a millimetre-sized chip is not trivial. Slow light concepts are an appropriate solution, if propagation losses are kept acceptable. Here we use a low-loss 1.5 mm-long photonic crystal waveguide to demonstrate both notch and band-pass microwave filters that can be tuned over the 0 50-GHz spectral band. The waveguide is capable of generating a controllable delay with limited signal attenuation (total insertion loss below 10 dB when the delay is below 70 ps) and degradation. Owing to the very small footprint of the delay line, a fully integrated device is feasible, also featuring more complex and elaborate filter functions. ; This work was funded by the European Union under the project GOSPEL (grant 219299) and by the Valencian Government (Prometeo GVA 2008-92). We thank S. Hughes and P. Lalanne for enlightening discussion about the impact of disorder in photonic crystal waveguides. ; Sancho Durá, J.; Bourderionnet, J.; Lloret Soler, JA.; Combrie, S.; Gasulla Mestre, I.; Xavier, S.; Sales Maicas, S. (2012). Integrable microwave filter based on a photonic crystal delay line. Nature Communications. 3:1-9. https://doi.org/10.1038/ncomms2092 ; S ; 1 ; 9 ; 3 ; Seeds, A. Microwave photonics. IEEE Trans. Microwave Theory Tech. 50, 877–887 (2002). ; Capmany, J. & Novak, D. Microwave photonics combines two worlds. Nat. Photon 1, 319–330 (2007). ; Yao, J. P. Microwave photonics. J. Lightwave Technol. 27, 314–335 (2009). ; See special technology focus on microwave photonics. Nat. Photon 5, 723–736 (2011). ; Capmany, J., Ortega, B. & Pastor, D. A tutorial on microwave photonic filters. J. Lightwave. Technol. 24, 201–229 (2006). ; Long, J. et al. A tunable microstrip bandpass filter with two independently adjustable transmission zeros. IEEE Microw. Wireless Compon. Lett. 21, 74–76 (2011). ; Velez, A. et al. ...
