Optical RAM and flip-flops using bit-input wavelength diversity and SOA-XGM switches

Christos Vagionas*, Dimitrios Fitsios, George T. Kanellos, Nikos Pleros, Amalia Miliou

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

33 Citations (Scopus)


In this paper, we demonstrate a novel RAM cell based only on three traveling waveguide semiconductor optical amplifier-cross gain modulation (SOA-XGM) switches. The RAM cell features wavelength diversity in the incoming bit signals and provides Read/Write operation capability with true random access exclusively in the optical domain. Two of the SOA-XGM switches are coupled together through an 70/30 coupler to form an asynchronous flip-flop, which serves as the memory unit. Random access to the memory unit is granted by a third SOA-ON/OFF switch and all three SOAs together form the proposed RAM cell. Proof-of-principle operation is experimentally demonstrated at 8 Mb/s using commercial fiber-pigtailed components. The distinctive simplicity of the proposed RAM cell architecture suggests reduced footprint. The proposed flip-flop layout holds all the credentials for reaching multi-Gb/s operational speeds, if photonic integration technologies are employed to obtain wavelength-scale waveguides and ultrashort coupling lengths. This is numerically confirmed for 10 Gb/s using a simulation model based on the transfer matrix method and a wideband steady-state material gain coefficient.

Original languageEnglish
Article number6251991
Pages (from-to)3003-3009
Number of pages7
JournalJournal of Lightwave Technology
Issue number18
Publication statusPublished - 10 Sep 2012


  • Optical flip-flop
  • optical memory
  • optical signal processing
  • semiconductor optical amplifier (SOA)
  • transfer matrix method (TMM)


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