The Research Of Novel Ofdm Technology In Optical Fiber Transmission Systems

Optical orthogonal frequency division multiplexing(OOFDM) has attracted much more attention recently, which has shown its extreme robustness against chromatic dispersion(CD), polarization mode dispersion(PMD), and high optical spectral efficiency(SE). It is easy to combine OOFDM with other advanced modulation techniques, such as wavelength division multiplexing(WDM) and polarization division multiplexing(PDM), to achive high CD and PMD robustness and high-speed optical fiber communication systems. Thanks to these techniques, the capacity of optical fiber transmission system with OOFDM could increase dramatically.In this dissertation, there are 4 novel OOFDM techniques are proposed and employed in OFDM-WDM-PON, intensity modulation and directly detection OFDM(IMDD OFDM), coherent optical OFDM(CO-OFDM),all optical OFDM(AO-OFDM), and multi mode fiber transmission based vertical cavity surface emitting laser(VCSEL) in data center respectively. All of the proposed system with the 4 novel OOFDM techniques are simulatelly and experimentally demonstrated. The main innovations are summarized as follows:1. OFDM-WDM-PON and IMDD OFDM with partial carrier filling(PCF) transmission systems are proposed and investigated. The four wave mixing(FWM) effect in OOFDM transmission is analyzed, and that it could be suppressed by PCF technique. The impacts of PCF patterns and PCF factor on transmission performance at 40 Gb/s over 100 km are simulated. The influence of power into fiber is examined to obtain the optimal value corresponding to the expected transmission distance. For further investigate the impacts of PCF in OOFDM transmission systems, IMDD OFDM based PCF transmission systems are experimentally demonstrated. Experiment results show that the best performance could be achived as the PCF with every few subcarrier filling zero, i.e., the FWM and noise in IMDD OFDM transmission system is suppressed well.2. Wavelet packet transform(WPT), which is one of the overlapped transforms with a longer symbol duration and hence yields a better spectral containment, is proposed as an alternate to replace FFT in traditional OFDM in optical fiber communications, i.e., wavelet packet transform OFDM(WPT-OFDM). In this dissertation, IMDD WPT-OFDM and coherent optical WPT-OFDM(WPT CO-OFDM) are proposed and analyzed. The simulation results show that it is feasible to introduce WPT-OFDM into optical fiber transmission systems. The performance of WPT CO-OFDM systems, with different lengths of quadrature mirror filter(QMF) pairs and different wavelet mother functions, are investigated and compared to that of their counterpart FFT-CO-OFDM systems over a fiber link. Simulation results show that some developed wavelet mother functions are suitable for OOFDM transmission systems. An experiment is conducted to verify the proposed IMDD WPT-OFDM transmission performance through 75 km SSMF. The experiment results show that WPT-OFDM could be as one of the alternates in IMDD optical fiber transmission systems.3. Asymmetrical receiver and and transmitter in high speed AO-OFDM systems are proposed to overcome the limitation of so-called electronic bottleneck, i.e., several common optical coherent receivers are adopted to receive the AO-OFDM signal partially from the optical band-pass filter(OBPF) in parallel. The OBPF is employed to splite the AO-OFDM signal into sevral parts of same bandwidth with matching the bandwith of adopted common coherent receiver. A Tb/s AO-OFDM transmission based optical FFT(OFFT), which is performed by cascaded Mach-Zehnder delay interferometers(MZDIs), is proposed and analyzed. Each optical subcarrier is encoded with 112 Gb/s PDM-QPSK signal. In addition, the sensitivity of gate width in all optical sampling using electro-absorption modulator(EAM) for AO-OFDM transmission systems without dispersion compensation fibers(DCFs) is investigated.4. An intelligent control interface capable of performing both automatic adaptive subcarrier bit/power-loading and on-line transmission system performance monitoring for existing real time OOFDM test-beds is designed and experimentally implemented. Such work will not noly simplify the future progress in advanced OOFDM transceiver designs, but also open a wide door for incorporating more intelligent functions into the test-beds.5. Directly modulated uncooled OIL-VCSEL-based real-time dual-band OOFDM transceivers with tunability in both the optical and electrical domains, such as the wavelength and power of the master laser and the bias current of VCSEL respectively, have been experimentally demonstrated, for the first time, utilizing DACs/ADCs at sampling speeds as low as 4 GS/s. The adaptive OOFDM transmissions have been achieved experimentally in IMDD OM2 MMF. Meanwhile, over various OIL conditions that bring about significant variations in frequency response, the aggregated transceiver transmission capacities were investigated in this work as well.