An All-optical Switch Based On The Faraday Effect Of Rubidium

Comparing with electrons,photons have higher speed and larger information capacity.From electronic communication to optical communication,the channel of information transmission changes from wire to optical fiber,which improves the bandwidth of communication network by hundreds of times and reduces the transmission loss greatly.However in optical fiber communication,in-formation processing is still carried out by converting light into electricity,which limits the further improvement of communication rate.There is no strong electromagnetic interaction between pho-tons.The all-optical switch uses indirect nonlinear method to control signal,that is,using the pump beam to change the optical parameters of the medium,and then change the state of signal beam.The all-optical switch based on Faraday effect of rubidium realized in this paper can still obtain high fidelity signal when the background noise is strong.It has the advantage of noise robustness because of the narrow linewidth of Faraday atomic filter.The high fidelity signal transmitted by it has wide application value in satellite communication,unmanned monitoring,ocean optical com-munication and other fields.In this paper,the 420 nm(5S_1/2?6P_3/2)Faraday atomic filter using rubidium vapor chamber as magneto-optical medium,is used as the basic structure in the all-optical switch with another 780 nm transition(5S_1/2?5P_3/2)of rubidium atom.First of all,we study the 420 nm and 780 nm Doppler absorption spectra and saturated absorp-tion spectra of⁸⁵Rb and⁸⁷Rb.Secondly,we studied on the influence of temperature magnetic field on the experimental results in the low temperature and low magnetic field range by discussing the transmission spectrum of Rb Faraday atomic filter.Rb Faraday atomic filter is a part of all-optical switch in this project.Finally,the all-optical switch based on the Faraday effect of Rb atom is obtained by further reforming the Rb atom Faraday atom filter system.For the all-optical switch experiment,the results show that when the magnetic field is 80 Gs,the temperature of the atomic vapor chamber surface is 120? when the signal light and the pump light are required to have the same change trend,the pump back signal beam has the highest reverse pumping efficiency cor-responding to the ground state hyperfine energy level of the atom,and its transmission is 9.11%,which is 4.22 times of the highest transmission of the original Faraday atomic filter(the high state light intensity of the switch is the strongest,and the low state of the switch corresponds to the transmission light intensity without the pump beam);when the signal beam and the pump beam are required to change in the opposition,the pump beam pulls out the signal light corresponding to the atomic population on the hyperfine energy level of the atom,adjusts the surface temperature of the atomic vapor chamber to 110?,and obtains the transmission close to 0 in the low state(under this working condition,the low state light intensity of the switch is the weakest,and the high state corresponds to the intensity of all-optical switch without pump light).The all-optical switch using Faraday effect has not been reported yet.The all-optical switch presented in this paper provides a solution direction for the future design of all-optical delayer and all-optical logic structure.Finally,the paper points out that in the future,the practical all-optical switch will be made by using Faraday effect,which will improve its performance in switching speed,energy consumption,insertion loss and other aspects,and further envisages the possibility of using it to build an all-optical network.