Complex-Coefficient Microwave Photonic Filter Based on Orthogonally Polarized Optical Single-Sideband Modulation

A complex-coefficient microwave photonic filter with continuous tunability is proposed and experimentally demonstrated. The filter taps are based on a 360° tunable microwave photonic phase shifter, which is realized by orthogonally polarized optical single-sideband (OSSB) modulation. The experimental results are shown and regarded as good performance for the proposed filter. The phase shift for the two taps covers a full 360° range from 8 GHz to 26 GHz. Frequency responses with different center frequency are measured within 20–21 GHz with the full free spectral ranges (FSRs) of 185 MHz and 285 MHz, respectively.

A photonic transmission link with enhanced dynamic range by incorporating phase shifters in dual drive dual parallel Mach–Zehnder modulator

A linearization scheme is proposed for microwave photonic link to enlarge spurious free dynamic range using a dual-electrode dual parallel Mach–Zehnder modulator (MZM). This scheme employs phase control method to improve performance of the link by adjusting phase of radio frequency (RF) signals and bias voltages of optical modulator. Optical single sideband modulation is achieved through sub-modulators of dual parallel MZM which increases efficiency of the link. The simulated results show that third order intermodulation distortion is suppressed by 28 dB when the input RF signals are 9.1 and 9.5 GHz and noise floor is at −161 dBm/Hz. The spurious free dynamic range is also improved by 12.6 dB.

Peak-to-Average Power Ratio Reduction of Carrier-Suppressed Optical SSB Modulation: Performance Comparison of Three Methods

We compare the performances of three previously proposed methods to reduce the peak-to-average power ratio (PAPR) of the carrier-suppressed optical single-sideband (OSSB-SC) signal. PAPR of OSSB-SC signal becomes high due to the peaky Hilbert-transformed signal which is used for spectral suppression. Nonlinear phase shifts induced by high PAPR degrade OSSB-SC signal during fiber transmission. Previously, we proposed peak folding, peak clipping, and high-pass Hilbert transform methods to reduce the PAPR of OSSB-SC modulation. In this study, we numerically compare the effectiveness of proposed methods in a 10 Gbit/s non-return-to-zero (NRZ)-coded 100-km single-channel transmission link. Due to the reduced PAPR, peak folding and peak clipping can increase the self-phase modulation (SPM) threshold of the studied system by 2.40 dB and 2.63 dB respectively. The high-pass Hilbert transform method improves the SPM threshold by more than 9 dB.