InP QPSK Vector Modulator

  • Description

    This setup illustrates how passive PIC elements integrated with active semiconductor laser sections can be modeled by means of an examplary QPSK modulator design (a vector modulator, as described in [1]). The device consists of some InP electro-absorber sections accounting for the modulation and passive InP waveguides performing adjustable phase shifts (Figure 1). The junction elements are placed between passive and active parts of the circuit emulating distortions produced by the connection of the two different waveguides types.

  • Typical Results

    The phase is globally controlled by a variable parameter which accounts for voltage variations applied in the waveguide contacts. Small differences in lengths of the arms or phase changes introduced by the absorbers might provoke an unbalance in the quadrature components which can be adjusted by an additional contact in the middle waveguide. An exemplary constellation and eye diagram of the modulated QPSK signal are plotted in Figure 2 and Figure 3 respectively.

  • Further Information

    Keywords: EAM, Optical Waveguide, Phase Modulator, Photonic Integrated Circuits, PICs

    Similar demonstrations are available in VPIComponentMaker Photonic Circuits and on the VPIphotonics Forum.

    [1] C. R. Doerr, L. Zhang, A. L. Adamiecki, N. J. Sauer, J. H. Sinsky et P. J. Winzer, "Compact EAM-Based InP DQPSK Modulator and Demonstration at 80 Gb/s", OFC/NFOEC, page PDP33, 2007.

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