Ordinary inter-satellite optical includes at least three optical paths for acquisition, tracking and communication, the three optical paths work simultaneously and share the received power. An optimal structure of inter-satellite optical communication terminal with single working optical path at each of working stages of acquisition and communication is introduced. A space optical switch based on frustrated total internal reflection effect is applied to switch the received laser power between the acquisition sensor and the communication sensor between the stages of acquisition and communication, this is named as power fusion which means power is transferred for shutting down unused optical path. For the stages of tracking and communication, a multiple cells sensor is used to accomplish the operation of tracking while communication, this is named as function fusion which means accomplishing multiple functions by one device to reduce the redundant optical paths. For optical communication terminal with single working path structure, the total received laser power would be detected by one sensor for each different stages of acquisition, tracking and communication, the link budget would be maximized, and this design would help to enlarge the system tolerance and reduce the acquisition time.
This paper summarizes the results of a dynamic link attenuation probability study in inter-satellites homodyne BPSK optical communication system. The impacts of the pointing and tracking error on the coherence receiving power are investigated analytically. To evaluate the requirement of optical system aberrations, the link attenuation caused by the aberrations is analyzed. By means of numerical simulation, the probability density function and the cumulative distribution function of bit error probability are calculated by the frequency histogram method.
After over twenty years since the demonstration of the first QKD systems in 1989 there have been two categories of
QKD systems, namely fiber QKD systems and wireless QKD systems. The security of a practical QKD system over
wireless optical paths is degraded due to imperfectness of devices and channel loss. Very simple attacks, such as beamsplitting
attacks (BS), could jeopardize the security of polarization coding QKD systems. Among all the attacks photon
number splitting (PNS) is the most threatening one against the security of polarization coding QKD systems. The upper
bound for secure transmission length of free-space QKD systems based on polarization coding under PNS attacks is
provided here as well as the secure transmission criterion. The theoretic results predicted in this paper accord with
experimental results of Manderbach's work.
A solution is proposed, which combined with FSO communication and laser ranging in order to effectively integrate two
payloads. It is a transformation of feedback pulsed laser ranging. Laser ranging hardware and FSO communication
hardware share a lot in common. Detailed description of working principle, error analysis and elementary experiment
result is also included. The further analysis indicates that the measurement precision can reach sub-millimeter by
counting more ranging period. Moreover, when temperature varies 30°C, the measure distance varies 2.25cm. In this
case, temperature control is necessary for sub-millimeter measurement.
Different operation models of joint optical multi-band detection systems are provided here, corresponding to the different
characters of detecting probabilities of subsystems. It leads to a higher over-all detecting probability. The joint optical
detection system is able to be operated under different models when detection probabilities of subsystems are low or
there is big difference among the probabilities. When all the probabilities of subsystems are low, the joint optical
detection system directly conducts data fusing. If there is big difference among the probabilities of subsystems,
information from the subsystems is chosen before entering the fusion center. In this way, the false-alarm probability of
the joint optical detection system reduces obviously comparing with direct data fusion. So it also can reduce the
calculation of system and improve the competence of system.