Cascaded SOA FWM with non-uniform ASE seeding: expanding a low-Cost DWDM system from 12 to 20 channels

This paper extends a low-cost wavelength-division multiplexing (WDM) source from 12 to 20 dense wavelength-division multiplexed (DWDM) channels using a cascaded semiconductor optical amplifier (SOA) architecture — without requiring any coherent lasers. A second SOA stage, seeded by the 12-channel output of the first stage (derived from three non-uniformly spaced, spectrum-sliced ASE inputs from a single high-power LED), generates eight additional four-wave mixing (FWM) components. The non-uniform input spacing (0.3 THz and 0.4 THz) deliberately inhibits a fully populated frequency comb, producing a finite, structured, and manufacturable channel set. Performance reveals a practical trade-off: the three original inputs exceed 195 km, while the eight cascaded channels are limited to 25–100 km — fully viable for urban and distribution links. Compared with conventional laser-array DWDM systems, the proposed design offers significantly lower cost and complexity. Future experimental validation under real-world conditions is recommended, alongside simplified diagrams and application scenarios to improve accessibility for students and industry practitioners.

Four-wave mixing, semiconductor optical amplifier, ASE, spectrum slicing, cascaded SOA.

1. G. Keiser, Optical Fiber Communications, 5th ed. New York, NY, USA: McGraw-Hill, 2015. [Google Scholar] [Crossref]

2. R. Ramaswami, K. N. Sivarajan, and G. H. Sasaki, Optical Networks: A Practical Perspective, 3rd ed. San Francisco, CA, USA: Morgan Kaufmann, 2010. [Google Scholar] [Crossref]

3. H. Li, G. T. Kanellos, and D. Nesset, "Four-wave mixing in SOAs for wavelength conversion," IEEE Photon. Technol. Lett., vol. 22, no. 15, pp. 1124–1126, 2010. [Google Scholar] [Crossref]

4. K. Inoue and T. Mukai, "Signal wavelength conversion using four-wave mixing in semiconductor optical amplifiers," J. Lightw. Technol., vol. 14, no. 6, pp. 1237–1245, 1996. [Google Scholar] [Crossref]

5. J. Zhang, N. Cheng, X. Gao, Y. Li, and F. Zhao, "Performance enhancement of spectrum-sliced DWDM systems using semiconductor optical amplifiers," IEEE Photonics J., vol. 12, no. 3, pp. 1–9, 2020. [Google Scholar] [Crossref]

6. D. I. Forsyth, "210 km long incoherent DWDM spectrum-sliced system running at 10 Gb/s incorporating semiconductor optical amplifier (SOA) enhancements," Int. J. Res. Innov. Appl. Sci., vol. 11, no. 1, pp. 396–400, Jan. 2026. doi: 10.51584/IJRIAS.2026.11010034. [Google Scholar] [Crossref]

7. D. I. Forsyth and M. J. Connelly, "Spectrum-sliced wavelength conversion using four-wave mixing from a semiconductor optical amplifier," in Proc. Optical Amplifiers and Their Applications (OAA), Budapest, Hungary, 2005. [Google Scholar] [Crossref]

8. D. I. Forsyth, K. R. Tariq, and A. J. Abdullah Al-Gburi, "Fully spectrum-sliced four-wave mixing wavelength conversion in a semiconductor optical amplifier," Przegląd Elektrotechniczny, vol. 5, pp. 215–218, 2024. doi: 10.15199/48.2024.05.40. [Google Scholar] [Crossref]

9. D. I. Forsyth and A. J. Abdullah Al-Gburi, "A low cost, multi-wavelength optical source enabling independent WDM channels using a single SOA and ASE inputs," Int. J. Res. Innov. Appl. Sci., vol. 11, no. 3, pp. 1521–1532, 2026. doi: 10.51584/IJRIAS.2026.11030117. [Google Scholar] [Crossref]

10. R. Paschotta, "Four-wave mixing," in RP Photonics Encyclopedia. [Online]. Available: https://www.rp-photonics.com/four_wave_mixing.html. Accessed: Apr. 15, 2026. [Google Scholar] [Crossref]