Research On Photon Down Conversion Base On Optical Injection Semiconductor Laser

With the development of the information age,people have put forward higher requirements on the transmission rate and effective bandwidth of wireless communication systems.These factors have prompted the development of high-frequency microwave and millimeter-wave communication bands.However,high-frequency microwaves have great losses in both solid-state media and the atmosphere.The application of microwave photonics technology in wireless communication systems can solve the problems of communication bandwidth and transmission loss,and the emergence of radio-over-fiber technology.It is the best illustration,which is widely used in civil and military fields.How to effectively convert the high frequency microwave signal in the ROF system is a key technology.The traditional electrical frequency conversion method is limited by the common bandwidth limitation of the devices used,and at the same time,the signal distortion will be caused during the processing.The use of microwave photon frequency conversion technology has broken through the bottleneck in the field of electronics,reducing the bandwidth requirements of the device,and has strong anti-electromagnetic interference capability.In this paper,the microwave photon frequency conversion method with mature technology is introduced.The principle of electro-optical modulation optical heterodyne detection frequency conversion scheme is analyzed.Based on this,a photon down conversion based on single sideband light injection semiconductor laser is proposed.The cascading DWDM is used for filtering and then injected into the slave laser.After the injection is locked,the light injected by the main laser can be amplified with high fidelity while retaining the original phase information,so that a high-quality coherent local oscillator light source can be obtained,and the local oscillator is to be the variable frequency light is input into the same photodetector.Due to the frequency difference between the two input lights,the heterodyne signal output can be finally obtained to achieve down-conversion.Using this principle,an experimental scheme was designed.It is verified by experiments that different nonlinear output states are obtained under different light injection conditions,and the characteristics are different in the output state according to the comparison between the spectrum and the spectrogram.Using three-stage cascaded DWDM for filtering experiments,the carrier and +1-order sidebands have been suppressed by 50.28 dB and 28.49 dB,respectively.In the experiment,by changing the wavelength difference of the light input into the photodetector,the down-converted signal output of 100 M,500M,1GHz,2GHz is obtained,the spurious suppression ratio is greater than 30 dB,and the conversion gain is greater than-59 dB.The system maintains the polarization maintaining performance,which increases the system's conversion gain by 3dB and the spur suppression ratio by 2dB.Finally,the system's error vector magnitude(EVM)and spurious-free dynamic range(SFDR)are tested.The scheme uses the injection locking to generate the local oscillator,so the two beams that perform the beat frequency have good coherence,and provide a high-stability,large-bandwidth optical frequency conversion method.