Compensation Of Dispersion-induced Power Fading Research Articles

All-Optical Double Spectral-Efficient RoF Link With Compensation of Dispersion-Induced Power Fading

An all-optical radio-over-fiber (RoF) link with double spectral-efficient transmission and compensation of chromatic dispersion-induced power fading is proposed and experimentally demonstrated. At the central office, a commercial dual-polarization quadrature phase-shift keying modulator is utilized to produce a polarization-multiplexed signal composed of two modulated microwave vector signals and an unmodulated optical carrier. At the remote node, by adjusting the polarization controller to introduce a proper phase shift to the unmodulated optical carrier, the two vector signals can be demodulated respectively and dispersion-induced power fading can be compensated simultaneously. The link performance is evaluated by error vector magnitude and bit error rate.

Compensation of dispersion-induced power fading with adjustment-free operation

A scheme for compensation of dispersion-induced power fading is proposed and experimentally demonstrated. The system transmits two modulated laser lights via a wavelength division multiplexer and a wavelength division demultiplexer. By optimizing the power ratio and the phase difference between the two modulated signals, the dispersion-induced power fading can be adequately compensated. A key significance of our approach is that no adjustments are required when the input radio frequency signal scans over a broad bandwidth of 1 to 12 GHz. We successfully demonstrate the compensation of the power fading for both 20- and 30-km fiber links. An improvement of spurious-free dynamic range is also achieved.

Transmission of dual-chirp microwave waveform over fiber with compensation of dispersion-induced power fading.

We propose a microwave photonic link to transmit a dual-chirp microwave waveform over fiber with compensation of dispersion-induced power fading. In a center office (CO), we use a polarization-dependent dual-parallel Mach-Zehnder modulator (DPMZM) which is driven by a radio frequency (RF) carrier and a baseband single-chirped waveform to realize carrier-suppressed dual-sideband (CS-DSB) modulation at two orthogonal polarization states. When the CS-DSB optical signal is detected by a photodetector (PD) at a base station (BS), the dual-chirp waveform is generated. However, along with the transmission to different BSs before emission, the chromatic dispersion of fiber will cause power fading. In our link, we can simply adjust the polarization controller (PC) in each BS to compensate for the dispersion-induced power fading for different transmission distances and RF carrier frequencies. Besides, the link can realize one to multitransmission with shared dual-chirp microwave source in CO for radars. The proposed scheme is theoretically analyzed and experimentally verified.

Compensation of Dispersion-Induced Power Fading in Analog Photonic Links by Gain-Transparent SBS

We demonstrate an analog photonic link with compensation of dispersion-induced power fading based on gain-transparent stimulated Brillouin scattering (SBS) induced carrier processing. Gain-transparent SBS introduces a phase shift selectively to the optical carrier. By properly adjusting the phase shift, the frequency response of the analog photonic link is shifted. The dispersion-induced power fading can thus be compensated at any working frequency. We demonstrated dynamic compensation of the power fading in photonic links over two transmission distances of 25 and 40 km in standard single mode fibers (SMFs). With gain-transparent SBS, the linearity of the analog photonic link is also improved. The spurious-free dynamic ranges of the proposed links over 25 and 40 km SMFs are measured to be 106.14 dB·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> and 105.34 dB·Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> and are improved by 35.15 dB · Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> and 35.86 dB · Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> , respectively. The transmission of 2 Gb/s 4-QAM and 4 Gb/s 16-QAM discrete multitone signals at 18 and 14 GHz microwave carrier frequencies are experimentally demonstrated with the lowest EVM of 12%.

An Analog Photonic Link With Compensation of Dispersion-Induced Power Fading

A simple and low cost analog photonic link with the compensation of dispersion-induced power fading is proposed and demonstrated using a dual-electrode Mach-Zehnder modulator. In the proposed link, the modulator is single-electrode driven to realize a novel double-sideband (DSB) modulation. By adjusting the dc bias of the modulator, the frequency response of a dispersive link can be controlled to compensate the power fading at any working frequency. Experimental results show that the power fading in a conventional DSB modulated link after fiber transmission over 25 and 50 km can be both successfully compensated in the proposed link, and the spurious-free dynamic range at 12 GHz of a link with 25 km of single-mode fiber is improved by 11.6 dB.

Flexible compensation of dispersion-induced power fading for multi-service RoF links based on a phase-coherent orthogonal lightwave generator.

A novel technique to simultaneously compensate dispersion-induced power fading for multi-service radio-over-fiber (RoF) links is proposed. At the central office (CO), a phase-coherent orthogonal lightwave generator (POLG) consisting of a polarization rotator (PR) and a single-driver Mach-Zehnder modulator (MZM) is used. By adjusting a polarization controller (PC) in the base station (BS), the phase difference between the orthogonal polarization carrier and two sidebands can be controlled, and the frequency response can be flexibly shifted for individual radio frequency (RF) service. We experimentally shift the destructive interference to the constructive interference at various frequencies for 25 km and 30 km fiber links. The performances of two services carrying 1 Gb/s on-off keying (OOK) data at 9 GHz and 16.6 GHz over a 30 km fiber in the proposed system show receiver sensitivity improvement of ∼12 dB at the bit error rate (BER) of 10(-3) compared with the conventional double sideband (DSB) modulation case.

Compensation of dispersion-induced power fading for highly linear radio-over-fiber link using carrier phase-shifted double sideband modulation.

A carrier phase-shifted (CPS) double sideband (DSB) modulation technique in radio-over-fiber (RoF) system is proposed and experimentally demonstrated. By tuning the biases in a single-drive dual parallel Mach-Zehnder modulator (SD-DPMZM), the optical carrier in the DSB spectrum acquires additional phase shift. The transmittance response of a dispersive RoF link is thus being controlled and shifted in the frequency domain. Experiments successfully turned the maximum transmission frequency to 10 GHz and 15 GHz for both 25 and 39 km fiber links. This is also a highly linear scheme, of which a spurious-free dynamic range (SFDR) of 111.3 dB·Hz2/3 is experimentally obtained.