Author: Jing Du 2015-12-24
Optical free-space data links, which provide potential increasein data capacity and spectral efficiency, has witnessed hugeprogress in certain wireless systems such as satellite communications,up-and-down links among mobile and stationary terminals,and indoor communication systems.Physical dimensions of light beams such as amplitude, phase, frequency/wavelength, time, and polarization have been widelyexplored to solve the emerging capacity crunch of optical communications.Beyond those well-known degrees of freedom oflight beams, in recent years, one important research field,known as the space-division multiplexing (SDM) technique usingthe space degree of freedom of light beams, has experimentallyproved its potential to increase the transmission capacityin optical communications.
Jian Wang’s group at Wuhan National Laboratory for Optoelectronics (WNLO), Multi-Dimensional Photonics Laboratory (MDPL),has been devoted to the research of SDM and encoding/decoding using orbital angularmomentum (OAM) beams and vector beams and achieved a series of progress:
1) PhD candidate Jing Du utilized OAM and nondiffractingcharacteristic of Bessel beams andexperimentally demonstrated12-m distance obstruction-free optical m-aryencoding/decoding in a free-space opticalcommunication system. This work was published on Optics Letters (vol. 40, no. 21,pp. 4827-4830, 2015).
2) Master studentYifan Zhao experimentally demonstrateda visible-light communication link exploiting high-basevector beam encoding/decoding. Using a single phase-onlyspatial light modulator, 16 states of vectorbeams representing hexadecimal numbers were generated. The bit-error rate (BER)was also evaluated,and zero error among all received hexadecimal numberswas achieved, showing favorable link communicationperformance using the high-base vector beam encoding/decoding. This work was published on Optics Letters (vol. 40, no. 21,pp. 4843-4846, 2015).
3) PhD candidate Long Zhu experimentally demonstrated data multicastingfrom a single Gaussian mode to multiple Besselmodes using a single phase-only spatial light modulator. Under the obstructed path conditions, obstruction-freedata-carrying N-fold Bessel modes multicasting was demonstratedin the experiment. AnN-fold multicasting of a 20 Gbit/s quadrature phase-shiftkeying (QPSK)signal from a single Gaussian mode to multipleBessel modes was also demonstrated. This work was published on Optics Letters (vol. 40, no. 23, pp. 5463-5466, 2015).
These works are partially supported by the National Basic Research Program of China (973Program) (2014CB340004), the NationalNatural Science Foundation of China (NSFC) (11274131, 11574001, 61222502), the Program for New Century ExcellentTalents in University (NCET-11-0182),and the Wuhan Science andTechnology Plan Project (2014070404010201).
Links of the published papers:
 Jing Du and Jian Wang*, "High-dimensional structured light coding/decoding for free-space optical communications free of obstructions," Opt. Lett. 40, 4827-4830 (2015).
 Yifan Zhao and Jian Wang*, "High-base vector beam encoding/decoding for visible-light communications," Opt. Lett.40, 4843-4846 (2015).
 Long Zhu and Jian Wang*, "Demonstration of obstruction-free data-carrying N-fold Bessel modes multicasting from a single Gaussian mode," Opt. Lett. 40, 5463-5466 (2015).
Figure 1 Hexadecimaland 32-ary encoding/decoding using Bessel beams.
Figure 2 Image transmission using vector beamencoding/decoding.
Figure 3 Concept and principle of N-fold Bessel modes multicastingfrom a single Gaussian mode.