Optical Vector Analysis With Improved Accuracy and Enhanced Dynamic Range

An optical vector analyzer (OVA) based on phase-shift (PS) technique is proposed and experimentally demonstrated, which enables improved accuracy and enhanced dynamic range. A carrier-suppressed optical double-sideband (ODSB) signal achieved by external modulation is used as the probe signal, which is then transmitted through a device under test (DUT). By photodetecting, a photocurrent carrying the frequency responses is generated. By scanning the wavelength of the optical carrier while extracting the magnitude and phase information of the photocurrent, the responses of the optical DUT are thus acquired. Since the carrier-suppressed ODSB signal has lower sensitivity to the nonlinearity and generates larger photocurrent than the intensity modulated ODSB signal, the proposed OVA has improved accuracy and enhanced dynamic range compared to the conventional PS-based OVA, which is comprehensively investigated in analytical analysis and simulation. In an experiment, the accuracy improvement is confirmed, and the enhancement of the dynamic range is evidently observed, which agrees well with the simulation results.