All-optical Signal Processing With SOAs And Optical Filters

All-optical signal processing can avoid the optical-to-electrical and electrical-to-optical conversions and has the advantages of large bandwidth,low power consumption and easy integration.It is expected to play an important role in the information processing and exchange of nodes in high-speed high-capacity optical communication network.The research of multi-channel all-optical signal processing integrated chip for multi-wavelength communication network is very important to promote the application of all-optical signal processing technology in optical communication network.Semiconductor optical amplifier(SOA)is widely used in all-optical signal processing due to its advantages of high nonlinear effect,low power consumption,high output efficiency,small size and easy integration.With the support of the “national key basic research and development plan(project 973)” and the “national science fund for distinguished young scholars”,this thesis mainly studies the alloptical signal processing based on the scheme with SOAs and optical filters,aiming to develop a monolithic integrated chip for multi-channel all-optical signal processing.The research work and contributions of this thesis are summarized in the following aspects:(1)A novel scheme with SOA and Fano filter is proposed to improve the performance of all-optical wavelength conversion.After the realization of 40 Gbit/s all-optical wavelength conversion with SOA and gaussian filter,a novel scheme with SOA and Fano filter is proposed.Using the steep transmission spectrum of Fano filter,the output power at the carrier wavelength can be suppressed while filtering out the blue-shifted detuning frequency chirp.In simulation and experimental investigation,the new scheme is demonstrated with improved output signal quality,comparing with the conventional gaussian filter scheme.In the experiment,at the rate of 40 Gbit/s,the optimal Q value of the converted signal increased from 5.7 to 6.9.(2)A monolithic integrated chip that integrates SOAs and optical filters for multichannel all-optical signal processing is developed.The design principle and method of onchip integrated devices are studied,and the designs of on-chip SOA,MMI(multi-mode interferometer),DI(delay interferometer)filter and AWG(array waveguide grating)filter are completed.The exploration and calibration of technological parameters such as photolithography process,etching process and electrode production are carried out,which laid a technological foundation for the design and fabrication of In P based monolithic integrated chip.Finally,the fabrication of monolithic integrated chip for multichannel alloptical signal processing is realized.There are 9 functional devices on this chip,including long SOA for nonlinear effect,short SOA for optical signal amplification,1×2MMI,2×2MMI,phase shifter,DI filter,AWG filter,etc.,besides passive waveguide for input/output coupling and transmission.The test platform of the chip is built to evaluate the performance of SOA and filters on chip.The test results show that the gain characteristics and voltage-current characteristics of SOA are good,the extinction ratio of DI is greater than 17 d B,the FSR of DI(free spectrum range)is about 1.5 nm,the tuning range of DI is more than half of FSR,the suppression ratio of AWG channels is more than 20 d B,and the channel spacing is about 3.3 nm.(3)The monolithic integrated chip with SOA and filters is used to demonstrate multichannel all-optical format conversion.It realizes simultaneous conversion from NRZOOK(Non return to zero on-off keying)to RZ-OOK(Return to zero on-off keying)of 4×40 Gbit/s,and the average power penalty between channels is less than 1 d B.Furthermore,4×50 Gbit/s NRZ-QPSK(Non return to zero quadrature phase shift keying)is converted to RZ-QPSK(Return to zero quadrature phase shift keying)simultaneously,and the average power penalty of the single channel is about 3 d B.In conclusion,this thesis proposes a scheme with SOA and filter to improve the performance of wavelength conversion.A monolithic integrated chip which can realize multi-channel all-optical signal processing has been developed successfully.Four-channel simultaneous format conversion is realized based on the integrated chip.The research work of this thesis promotes the research of all-optical signal processing integrated chip based on SOA,which has theoretical significance and practical value.