Optical intersatellite data transmission with phase conjugate mirror for formation flying

Abstract

We propose a new optical intersatellite communications system with a phase conjugate mirror (PCM) in formation flying (FF). In conventional optical intersatellite communications, high-accurate target acquisition and tracking are required for both the transmitter and the receiver. In our system with a PCM, when a control beam from the receiver is captured by a PCM in the transmitter, the signal beam from the transmitter introduced back to the receiver as its phaseconjugate replica. Thus, it is not necessary for the transmitter to target the receiver. Another advantage of using a PCM is that we can utilize spatial filtering. Background noise by sunlight with the laser wavelength can also be efficiently suppressed by a spatial phase modulation/demodulation and filtering processes using phase compensation by the PCM, which leads to the improvement of the signal-to-noise ratio (SNR) and hence provides high data transmission rates in the system. In order to efficiently filter out the background noise, a large beam propagation angle is required in spatial filtering. We spatially modulate the background noise by the diffuser and reduce the beam diameter by the expansion/downscale optical system as a method to enlarge the beam propagation angle.In this paper, we show that our system can separate the noise from the signal by using the expansion/downscale optical system even under spatial phase modulation. In the analysis, the SNR is 32.6[dB] at scale=8.0×10 4 , when a spatial phase modulation by the diffuser is θ=1.5×10 -5 [rad].