Role of amplified spontaneous emission in optical free-space communication links with optical amplification: impact on isolation and data transmission and utilization for pointing acquisition and

摘要

Abstract: We investigate the role of amplified spontaneous emission (ASE) produced by an optical booster amplifier at the transmitter of free-space optical communication links. In a communication terminal with a single telescope for both transmission and reception, this ASE power has to be taken into account in connection with transmit-to-receive channel isolation, especially since it partly occupies the same state of polarization and the same frequency band as the receive signal. We show that the booster ASE intercepted by the receiver can represent a non-negligible source of background radiation: In a typical optical intersatellite link scenario, the ASE power spectral density generated by the booster amplifier at the transmitter and coupled to the receiver will be on the order of 10$+$MIN@20$/ W/Hz, which equals the background radiation of the sun. Exploiting these findings for pointing, acquisition, and tracking (PAT) purposes, we describe a patent-pending PAT system doing without beacon lasers and without the need for diverting a part of the data signal for PAT. Utilizing the transmit booster ASE over a bandwidth of e.g. 20 nm at the receiver, a total power of about $MIN@46 dBm is available for PAT purposes without extra power consumption at the transmitter and without the need for beacon lAser alignment. !11