Yuchen Shao

Optical RF Self-Interference Cancellation by Using an Integrated Dual-Parallel MZM

An optical approach to implement radio-frequency (RF) self-interference cancellation using an integrated dual-parallel Mach–Zehnder modulator (DP-MZM) is proposed and demonstrated experimentally. The received signals and the reference signal are converted into optical domain via the sub-MZMs (MZM1 and MZM2) in the DP-MZM, which are biased at the quadrature point and the minimum point with the output of double sideband with carrier signal and double sideband with carrier-suppressed signal, respectively. It avoids the optical interference at the combining Y branch waveguide. The time and the amplitude matching conditions for cancellation between the reference signal and the interference signal are completed by the electrical tunable time delay line and the phase shifter in the MZM2 path. A cancellation depth larger than 80 dB is obtained for the single-frequency signal of 2.4, 5, 8, and 10 GHz. For the bandwidth of 100 MHz, cancellation depths as high as 35.8, 33.1, and 38.3 dB are realized at frequencies of 2.4, 5, 8, and 10 GHz, respectively.

RF self-interference cancellation using phase modulation and optical sideband filtering

A novel optical approach to implement RF self-interference cancellation for full-duplex communication using phase modulation and optical sideband filtering is proposed and demonstrated experimentally. Based on the inherent out-of-phase property between the left and right sidebands of phase-modulated signal and optical sideband filtering, the RF self-interference cancellation is achieved by tuning the delay time and amplitude in the optical domain. RF self-interference cancellation for single frequency and microwave with various bandwidths of 1, 5, and 10 MHz is experimentally demonstrated to verify the proposed technique.

Filtering properties of the tunable microwave photonic filter with stimulated Brillouin scattering

Abstract. The filtering properties of a continuously tunable single-passband microwave photonic filter based on stimulated Brillouin scattering (SBS) are investigated. The filter utilizes the advantage of combining phase-modulated RF signal and dual-sideband suppressed-carrier pump signal to achieve the SBS-based tunable narrowband filtering. The effects of pump power on the out-of-band rejection (OBR) and 3-dB bandwidth, the optical fiber structure on the resonant sideband, and input RF signal power on the OBR and 3-dB bandwidth are analyzed theoretically and experimentally. The results show that the pump power has the potential of increasing the OBR and tuning 3-dB bandwidth, whereas the RF signal power has nearly no influence on the two parameters.

Bandwidth tunability of stimulated Brillouin scattering based microwave photonic filter

Stimulated Brillouin scattering (SBS) in optic fibers has potential applications for microwave photonic signal processing. The bandwidth tunability of SBS based microwave photonic filter (MWF) has been investigated theoretically and experimentally. Two tuning approaches, one is to alter the pump wave power and the other is to control the pump wave spectrum, are presented. The results show the latter one has more flexibility than the former one to tune the bandwidth of SBS based MWF.

Photonic enabled RF self-interference cancellation for full-duplex communication

Photonic enabled RF self-interference cancellation for full-duplex communication by using phase modulation and optical sideband filtering is proposed. Based on the inherent out-of-phase property between the left and right sidebands of phasemodulated signal and optical sideband filtering, the RF self-interference cancellation is achieved by tuning the delay time and amplitude in the optical domain. The operational principle of the proposed scheme is theoretically analyzed and the feasibility is experimentally demonstrated. The optical sideband filtering for the phase modulated signals is measured and the RF self-interference cancellation at different carrier frequencies is studied. The results show a good performance of the proposed photonic scheme for RF self-interference cancellation. The full-duplex communication based on the photonic enabled RF self-interference cancellation is also investigated.

RF self-interference cancellation for full-duplex communication with microwave photonic technique

RF self-interference cancellation for Full-Duplex communication with a microwave photonic technique is proposed and demonstrated experimentally. It is based on an integrated dual-parallel Mach-Zehnder modulator (DP-MZM), where the sub-MZMs (MZM1 and MZM2) are biased at the quadrature point and the minimum point, respectively. It avoids the optical interference at the combining Y branch waveguide. The self-interference cancellation performance for 2.4 GHz, the standard of wireless service of WiFi (IEEE 802.11), is investigated. The cancellation depth as high as 83 dB is obtained for single frequency signal. And for the signal with a bandwidth from 10 MHz to 100 MHz, the cancellation depth larger than 44 dB is completed.

Polarization multiplexed dual-loop OEO based on a phase-shifted fiber bragg grating

A photonic method for microwave signal generation by utilizing the optoelectronic oscillator (OEO) is presented. The OEO is mainly composed of the polarization multiplexed double loops to suppress the side modes, and the phase-shifted fiber Bragg grating (PS-FBG) to select the oscillation frequency. The experimental results show that the generated microwave signal can be tuned from 1 to 4 GHz by changing the wavelength of the light source. By virtue of the polarization multiplexed dual-loop, the suppression ratio of the side mode can be as high as 61 dB. The phase noise with different fiber length in the loop and at different frequency is measured and the results are discussed. The phase noise of −116 dBc/Hz@10 kHz is achieved.

Optical RF self-interference cancellation for full-duplex communication using phase modulation and sideband filtering

A novel optical approach to implement the RF self-interference cancelation for full-duplex communication using phase modulation and sideband filtering is proposed and demonstrated experimentally. By using the inherent out of phase property between the left and right sidebands of phase-modulated signal, and tuning the delay time and amplitude in optical domain to align the reference signal with the interference signal, the RF self-interference cancellation is achieved. The experimental results show that, for both 5GHz and 8GHz, the system can achieve 61- and 35-dB cancellation depth for single frequency and 1MHz bandwidth, respectively.

Detection of low-power RF signals using a tunable optoelectronic oscillator

A tunable optoelectronic oscillator (OEO) for detecting low-power radiofrequency (RF) signals is proposed and experimentally demonstrated. The tunable OEO is mainly composed of a tunable laser source, a phase modulator, a phase-shifted fiber Bragg grating (PS-FBG) and a photodetector. The PS-FBG is used as a notch filter to remove one sideband of the phase-modulated signal to realize the phase modulation to intensity modulation conversion, which determines the main oscillation mode of the OEO. The frequency of the RF signal under detection can be estimated by the frequency difference between the optical carrier from the TLS and the notch of the PS-FBG. The RF signal as low as -75 dBm is detected with a dynamic range of 80 dB. The RF signals from 1.5 to 4.5 GHz are selectively amplified with a gain of about 7dB.