As the key techniques in Synthetic Aperture Ladar (SAL), balanced optical heterodyne receiver technology is studied in this paper. Firstly, the influence of local oscillation intensity noise on single-detector heterodyne receiver's performance is analyzed theoretically, and is verified through the optical heterodyne experiment by use of a diode pumped solid-state laser.Secondly, dual-detector optical heterodyne receiver model-the core model of balanced optical heterodyne receiver technology is discussed systemically, whose biggest feature is to remove intensity noise of local oscillation. Several key factors of dual-detector optical heterodyne receiver, including unmatched detector frequency responses, unequal path lengths, beam splitter or coupler's attenuation and so on, are discussed in detail. Proposals are given on the actual production of dual-detector optical heterodyne receiver.Finally, based on dual-detector optical heterodyne receiver model, polarization independent heterodyne balanced receiver is discussed ,which can eliminate the impact of polarization fluctuations of signal light on optical heterodyne receiver's performance; and then an improvement model-T-detector heterodyne receiver is proposed ,which can completely eliminate local oscillation factor of intermediate frequency signal, resulting in total elimination of the local oscillation intensity noise's impact on the receiver sensitivity. |