Performance Analysis And Key Technologies Research On Broadband Analog Photonic Links With High Dynamic Range

Analog photonics link offers several advantages, including low loss, broadband, increased dynamic range, it has already become the research focus of microwave photonics. Analog photonics link is considered as a promising technique and has important application backgrounds in civilian communication, radar, electronic warfare, radio astronomy and aerospace, etc. A deep-in-sight research has been carried out in this thesis, which provides new solutions aiming the limited bandwidth, the nonlinear distortions and the dispersive fiber induced power fading in analog photonic links. The innovative works of the thesis are listed as follows:1. A special transmitter design based on parallel intensity and phase modulators is presented, which can eliminate the fiber dispersion induced power fading. Thanks to the complementary power fading fuctions for the phase and intensity-modulated links, a flat frequency response over0-18GHz operation bandwidth is achieved over a34km link, with a fluctuation lower than3dB. This approach is a promising candidant for the high-performance transmission of the broadband RF signal over long-haul anglog photonics link.2. A novel technology based on dual-output MZM and polarization multiplexing is proposed to achieve the multi-octave operation of the analog photonics link. Experiment results show that the second-order harmonic distortion is suppressed by35.8dB, with an18dB improvement for the second-order spurious-free dynamic range (SFDR). By using this proposed approach, the harmonic disturbances are eliminated and the multi-octave operation is made possible.3. Innovative research work has been carried out concerning the elimination of the nonlinear distortion and optimization of the SFDR. Two kinds of techniques-both all-optical pre-distortion and digital signal processing (DSP) based post-compensation are proposed and experimentally investigated:(1) An optical carrier band (OCB) processing approach is proposed to suppress the third-order inter-modulation distortions (IMD3). By independently controling the phase of the OCB, the IMD3terms induced by the different optical spectrum contributors can cancel each other. A34dB suppression of the IMD3is achieved in the experiment. No additional processing in the electronic domain is required and the simple structure is preserved at the same time.(2) A simple and effective DSP linearization technique is proposed. This technique shows a robust signal reconstruction independent from knowing the specific transfer fuction of the system. The proposal is easy to be implemented as only the bias angle of the MZM needs to be known by the algorithm. It is also worth noting that this technology is capable of compensating both the inter-modulation and cross-modulation distortion for ultra-wideband analog photonics link, which makes it especially attractive.A DSP algorithm, which is capable of simultaneously compensating the nonlinear distortions induced by the electrical pre-and post-amplifier, and that of the MZM, is proposed. Through using high performance pre-and post-amplifier, an improved noise figure and link gain are obtained while the nonlinearity of the electrical amplifiers can also be compensated by the proposed algorithm. Experimentally, a record SFDR of128.3dB in1Hz bandwidth is achieved for a digitizer noise limited analog photonics link. The measured noise figure and gain of the photonics link are8.9dB and27.5dB, respectively. As far as we know, advanced world standard has been reached by using this approach.