ABSTRACT
Satellite free-space optical (FSO) communication is very promising in improving the bandwidth and capacity of space information networks in the future. However, the inter-satellite transmission distance of over 1000 km leads to unstable optical beam pointing, acquisition, and tracking and then generates optical power jitter by a large margin before detection-demodulation. Therefore, it is difficult to realize high-stability and long-time FSO communication between satellites due to the generated bit error rate (BER) by jitter. In this paper, we report an autonomously self-designed and high-integration laser communication payload (LCP) and on-orbit-demonstrated inter-satellite 145 min, zero-BER FSO stable communication with a line rate of 2.8 Gbps. Moreover, based on the inter-satellite laser communication link, a video phone was clearly implemented for more than 10 min, and authentic user data transmitted 459,149 packets, achieving results of zero-packet loss. Summarily, this on-orbit experiment demonstrated an excellent performance of the LCP owing to the distinctive design of integrating a high-power amplifier and low-noise amplifier optical amplification function. Our space mission was successfully completed, and the on-orbit demonstration results may offer a significant reference for the field of satellite laser communication and space information networks.
ABSTRACT
In recent years, the thriving satellite laser communication industry has been severely hindered by the limitations of incompatible modulation formats and restricted Size Weight and Power (SWaP). A multi-modulation compatible method serving for free-space optical (FSO) communication has been proposed assisted by chirp-managed laser (CML). The corresponding demonstration system has been established for realizing free-switching between intensity (OOK) and phase modulation (RZ-DPSK). The feasibility and performance of system have been evaluated sufficiently when loading with 2.5 and 5 Gbps data streams, respectively. Additionally, a control-group system has been operated utilizing Mach-Zehnder modulator (MZM) for comparison between CML-based and MZM-based compatibility solutions. The OOK receiving sensitivities of CML-based system are -47.02 dBm@2.5 Gbps and -46.12 dBm@5 Gbps at BER of 1×10-3 which are 0.62 dB and 1.11 dB higher than that of MZM; the receiving sensitivities of RZ-DPSK are -50.12 dBm@2.5 Gbps and -47.03 dBm@5 Gbps which are 0.79 dB and 0.47 dB higher than that of MZM respectively. Meanwhile, CML-based transmitter abandoned the traditional modulator and its complicated supporting devices which can effectively contribute to the reduction of SWaP. The CML-based system has been proven to have the compatibility between intensity and phase modulation while also possesses a miniaturized design. It may provide fresh thinking to achieve a practical miniaturization system for satisfying the requirements of space optical network in future.
ABSTRACT
Shortwave infrared (SWIR) polarimetric imaging has been found very effective in various applications. However, the low resolution of the SWIR camera severely limits the capacity of this technique. Image reconstruction methods have been developed to improve the spatial resolution, but these methods typically do not consider the polarized information that the images may contain. In this paper, we propose a high-resolution reconstruction method for SWIR images based on the spatial information of visible images without losing polarized information in the SWIR image. Experimental results demonstrate that this method is feasible to reconstruct high-resolution polarized SWIR images. We have also demonstrated its potential application in image fusion.
ABSTRACT
Polarimetric dehazing methods have been proven to be effective in enhancing the quality of images acquired in turbid media. We report a new full-Stokes polarimetric camera, which is based on the division of aperture structure. We design a kind of automatic polarimetric dehazing algorithm and load it into the field programmable gate array (FPGA) modules of our designed polarimetric camera, achieving a real-time image haze removal with an output rate of 25 fps. We demonstrate that the image quality can be significantly improved together with a good color restoration. This technique might be attractive in a range of real-time outdoor imaging applications, such as navigation, monitoring, and remote sensing.
