Study On Balanced Detection Technology Of Synthetic Aperture Lidar

Synthetic Aperture Lidar(SAL) with higher imaging resolution and faster imaging speed has become a core technology of significant importance.High sensitivity detector technique is a key technology of SAL and Balanced Mixing Receiver has received much concern because its ability to eliminate the excess intensity noise and to work near Quantum Noise Limit(QNL).Firstly, the origin and power spectral distribution of radiation source (i.e. Solid-state Lasers) are introduced. It indicates that Quantum Noise comes from the quantum nature of laser and can not be cancelled with classical methods such as Balanced Detection, and that the primary noise component is Resonant Relaxation Oscillation(RRO) which can be activated by whatever distortion, and that the level of low frequency component of intensity noise depends mainly upon pump noise.Finally, based on the time-domain correlation function and frequency-domain power spectrum descriptions, we combine the effect assessment of noise suppression with imbalanced factors of balanced detection system and numerical calculations are proceeded. The results show that we should mainly concern the symmetry of detection system rather than the optical path length difference between the outputs of splitter and the inputs of photo-detectors, and that when the detector is imbalanced, the best noise suppression effect doesn't come from the accouplement of the foregoing optical path, and that the less balance the system is, the smaller Maximum Noise Suppression Ration(MNSR) it could realize and the optical path length difference decides whether or not the system works with MNSR.