A stable and broadband microwave photonic phase shifter based on the combined use of a linear chirped fiber Bragg grating and optical single-sideband(OSSB) modulation is proposed and experimentally demonstrated.The quality of the radio frequency(RF) signal is improved by the spectral separation delay processing. The theoretical fundamentals of the scheme are explained and the phase shift can be controlled linearly by the wave?length. of the light source. In the experiment, a full 360° phase shift with a 10 GHz bandwidth can be achieved and tuned dynamically, continuously, and stably.
Path computation elements(PCEs)are employed to compute end-to-end paths across multi-domain optical networks due to the advantages of powerful computation capability.However,PCEs’location selection is still an open problem which is closely related to the communication overhead.This paper mainly focuses on the problem of PCEs’location selection to minimize the overall communication overhead in the control plane.The problem is formulated as a quadratic integer programming(QIP)model,and an optimal decision rule is gained from the solution of the QIP model.Then based on the decision rule,a distributed heuristic algorithm is proposed for dynamic network scenario.Simulation results demonstrate the benefit and the effectiveness of our proposed approach by comparing it with random selection policy.
This paper presents the fundamental principles and recent advances in the field of linearity enhancement of Mach–Zehnder modulators in microwave photonic systems using all-optical signal processing.A review of the fundamentals and applications that implement the linearity improvement is also provided.
We propose and experimentally demonstrate a scheme of high-Q microwave photonic filter(MPF)using the techniques of self-phase modulation(SPM)spectrum broadening and third-order dispersion(TOD)com-pensation.The optical pulses from a mode-locking laser are spectrally broadened by the SPM in the highly nonlinear fiber.A wideband optical frequency comb with 365 spectral lines within 10-dB power variation from the highest spectral power is obtained.By applying a cubic phase modulation via a waveshaper,the effect of TOD which broadens the MPF passband is eliminated.The final implemented MPF has a Q-value as high as 296 and a tuning range of 700 MHz.
The principle of error vector magnitude (EVM) against modulator nonlinearity for vector modulation signal (VMS) transmission in radio-over-fiber (RoF) systems is theoretically and experimentally investigated. A highly linear modulation scheme is proposed and demonstrated using a single-drive dual parallel Mach-Zehnder modulator (MZM). This method improves EVM performance and enlarges the linear input dynamic range of the VMS transmission. An index of maximum allowable input power difference (MAIPD) that reflects the difference of upper input power limits between these two schemes is measured. An EVM limitation of 5% MAIPD has 5 dB. Both 16and 64-QAM results indicate that the proposed scheme supports VMS transmission better than the MZM one.
