All Optical Wavelength Conversion For Coherent Modulation Formats In Silicon-based Waveguides

With the acceletated pace of modernization,the popularity of information,and the increasing number of mobile users,the traditional communication systems can not satisfy the requirements of modern communications.There are two effective ways to make full use of the spectral bandwidth and increase the transmission capacity:one is the use of coherent modulation formats which can increase the bit information per symbol;the other is the multiplexing technologies to improve the number of channel and the sprctum efficiency.All optical wavelength conversion,which can improve the reuse rate of the wavelengths and avoid the blocking caused by wavelength collision,plays an extremely important role in the all optical wavelength-routing communication links.Meanwhile,owing to the high stability,high reliability,small size and low cost,integrated waveguides have been the long-term development direction for the optoelectronic devices.In this thesis,we have experimently demonstrated all optical wavelength conversion and multicasting for multi-level coherent modulation formats based on the four wave mixing effects in the slicon-based waveguides,which provides an valuable solution and reference for the integrated optical signal processing in all optical commucation networks.This thesis mainly includes three works:1.Besed on the silicon-on-insulator(SOI)waveguide,all optical wavelength conversion and multicasting are experimentally implemented for quadrature phase shift keying(QPSK)and quardrature amplitude modulation(16QAM)coherent modulation formats.For QPSK signal,all optical waveleng conversion and 5-channel multicasting are realized for 20 Gbit/s QPSK signal with one and two continuous wave pumps.The eye diagrams,the constellation diagrams and the bit error rates(BERs)of the input signal,the converted idler and five multicasted idlers are detected.The power penalties of the converted and multicasted idlers are all less than 0.7 dB at the BER of 3×10-3.For 16QAM signal,the multicasted power penalties are less than 0.96 dB at the BER of 3.8×10-3.2.All optical wavelength conversion and multiplexing are realized for polarization division multiplexing(PDM),wavelength divixion multiplexing(WDM)and orthogonal frequency division multiplexing(OFDM)coheren modulation formats based on the SOI waveguide.All-optical wavelength conversion and multicasting is presented and experimentally demonstrated for PDM-QPSK signals with angled-polarization pumps in a single SOI waveguide.The measured power penalties of all these converted and multicasted idlers on both X and Y polarization states are less than 2.0 dB at the BER of 3×10-3.For the first time,all-optical wavelength conversion for WDM-compatible adapticely modulated OFDM signals in the SOI waveguide has been proposed,and the experiments have been demonstrated for 2×11.64 Gbaud/s OFDM signals with different modulation formats on different carriers.The transmission rates is improved by?12 Gbit/s without increasing the converted powe penalty.3.We have proposed a silcion-based silicon/silicon-rich nitride(Si/SRN)hybrid waveguides,which are experimentally demonstrated for the all optical wavelength conversion of coherent modulation formats.The silicon-based Si/SRN hybrid waveguides are designed and optimized using ModeSolution,and then are fabricated.The linear and nonlinear characterization of the silcion-based Si/SRN hybrid waveguides are analysised.The measured nonlinear kerr coefficient of the silicon-based Si/SRN hybrid waveguides is between that of Si and SRN.No obvious non-linear losses were observed at the current power level,which suggests that the proposed hybrid waveguides can handle higher powers.All optical wavelength conversion for 20 Gbit/s QPSK signal based this silicon-based hybrid waveguide are demonstrated.The calculated converted powe penalty is only 0.39 at the BER of 3”10-3,which is smaller than that in SOI waveguide.