Research On Optical Information Processing Based On Saturable Absorber

The age of Big Data,the rise of cloud computing and Internet of Things,higher and higher requirements are putting forward by growth of massive information.In order to solve the defects of low efficiency,large power consumption and slow response speed,which bring by traditional electrical component, all-optical information processing has already came into being.Optical computing,optical logic gates, optical switching and optical communication networks have been fruitful in recent years.A variety of materials applied to optical information processing are also emerging, like semiconductor, nano-materials, chemical polymer materials,and so on. Semiconductor materials are the most commonly used for optical information processing,and the saturated absorption characteristics of semiconductor materials has become a popular research object,which benefited from its optical information in the relevant applications.In this paper,we discuss the application of saturable absorber in all optical wavelength conversion and optical sensor in all-optical networks.(1) In order to meet the transmission rate demand of optical network growth by 26% rate every year,combineing multiple low-rate carriers is one of the suitable methods which can be regarded as a super-channel to be transmitted. In this paper,we study the performance of wavelength conversion by interleaved quadrature amplitude modulation orthogonal frequency division multiplexing (OFDM/OQAM) based on saturable absorber lasers with their four-wave mixing effect. The subcarriers are numerically simulated using 16-state quadrature amplitude modulation.The 256 channels of subcarriers are selected for OFDM modulation,and the subchannels are 8 channels.Each channel can reach to 30Gbaud/s and the super channel rate can reach to 960 Gbits /s.The simulation results show that the four-wave mixing in saturable absorber lasers is feasible for all-optical wavelength conversion in the wavelength division multiplexing super channel.In order to get rid of reception problem bring by traditional receiver.A new type of receiver are designed and proved in the paper.We also consider the wavelength conversion efficiency effects bought by the number of OFDM subcarriers, the DC offset of the saturable absorber laser and the PAM baseband modulation. 128,256,1024 channel carriers and raised cosine, root raised cosine two pulse filters are choosed to do a comparative study.The study also found that the cross-gain modulation of the superchannel on the pump seriously degrades the performance of the whole system, and the frequency detuning between the superchannel and pump has a great influence on the cross-gain modulation.The simulation results show that the system efficiency is better,when the pump power is twice the saturable absorber gain saturation power and the detuning frequency is set at 200 ?250GHz.(2) In the second part, the saturable absorber is combined with an optical sensor. A stable laser output is obtained by combining the saturable absorber frequency stabilization characteristics based on a ring fiber laser, and it is successfully applied to strain sensing. The non-pumped erbium doped fiber is used as the saturable absorber to form a narrow-band filter, and a high reflectivity fiber grating is used as the wavelength selective . It was found that the length of the saturated absorber had an effect on the performance of the photosensor. The simulation results show that the optical fiber sensor with saturable absorber is better than that saturable absorber absent. It is found that the saturated absorber has stabilizing effect on different wavelengths pump also, and the optimal length is 4m by simulating the influence of different wavelength pump light and different length saturable absorber on the performance of the sensor.