Digital optical phase control in ridge-waveguide phase modulators

The authors report a digital optical phase modulation concept based on depletion-edge-translation p-n junction GaAs/AlGaAs ridge-waveguide modulators. Digital modulation is achieved by integrating in series several discrete waveguide modulators with lengths related by successive factors of two. To illustrate the concept, the authors fabricated and demonstrated a three-bit digital phase modulator with 45 degrees resolution. This structure represents the first photonic integrated circuit that performs direct digital-electronic to analog-optical conversion.<
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