28 August 2009 The research of improving the efficiency of space coherent optical detection
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Proceedings Volume 7382, International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging; 738229 (2009) https://doi.org/10.1117/12.834907
Event: International Symposium on Photoelectronic Detection and Imaging 2009, 2009, Beijing, China
Abstract
Coherent optical detection technique has been widely used in communication and non-communication fields due to its advantages in handling kinds of modulation formats and offering improved sensitivity and signal to noise ratio. We present an acousto-optic signal processing system using coherent detection technique. Firstly the principles of Bragg diffraction and coherent optical detection are introduced. And then how to combine coherent detection with acousto-optic deflection to achieve signal processing is discussed. As to improve the efficiency of the space coherent optical detection, an approach that signal and reference beams are respectively injected into corresponding polarization-maintaining (PM) fibers before combining is put forward. In this way, the fluctuation of the state of polarization of the two beams is overcome. Through beam collimation, polarization-state control and Fourier transform (compression processing), the acousto-optic deflector is ensured to get higher diffraction efficiency over the whole frequency band of operation. Meanwhile, the impact that the surrounding environment has on the mixing of signal and reference beams is decreased, and the level of complexity and difficulty in optical system alignment is also reduced. At last, computer simulation has shown that the SNR is much depended on the linewidth of laser. When the coupling optical aperture and laser energy injection efficiency are ensured to meet demands, experiments have proven that, by injecting beam into PM fiber, the influence background light has on combining is weakened so that it is easier to keep polarization matched between signal and reference beams, and thereby the efficiency of coherent optical detection can be greatly improved.
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Hong-yan Jiang, Hong-yan Jiang, Ning He, Ning He, "The research of improving the efficiency of space coherent optical detection", Proc. SPIE 7382, International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, 738229 (28 August 2009); doi: 10.1117/12.834907; https://doi.org/10.1117/12.834907
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