The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.
References
[1]
Duntley, S.Q. (1963) Light in the Sea. Journal of the Optical Society of America, 53, 214-233. https://doi.org/10.1364/JOSA.53.000214
[2]
Hale, G.M. and Querry, M.R. (1973) Optical Constants of Water in the 200-nm to 200-μm Wavelength Region. Applied Optics, 12, 555-563. https://doi.org/10.1364/AO.12.000555
[3]
Pope, R.M. and Fry, E.S. (1997) Absorption Spectrum (380-700 nm) of Pure Water. II. Integrating Cavity Measurements. Applied Optics, 36, 8710-8723. https://doi.org/10.1364/AO.36.008710
[4]
Cochenour, B.M., Mullen, L.J. and Laux, A.E. (2008) Characterization of the Beam-Spread Function for Underwater Wireless Optical Communications Links. IEEE Journal of Oceanic Engineering, 33, 513-521. https://doi.org/10.1109/JOE.2008.2005341
[5]
Zeng, Z.Q., Fu, S., Zhang, H.H., Dong, Y.H. and Cheng, J.L. (2017) A Survey of Underwater Optical Wireless Communications, IEEE Communications Surveys & Tutorials, 19, 204-238. https://doi.org/10.1109/COMST.2016.2618841
[6]
Kaushal, H. and Kaddoum, G. (2016) Underwater Optical Wireless Communication. IEEE Access, 4, 1518-1547. https://doi.org/10.1109/ACCESS.2016.2552538
[7]
Zhu, S.J., Chen, X.W., Liu, X.Y., Zhang, G.Q. and Tian, P.F. (2020) Recent Progress in and Perspectives of Underwater Wireless Optical Communication. Progress in Quantum Electronics, 73, Article ID: 100274. https://doi.org/10.1016/j.pquantelec.2020.100274
[8]
Hu, L.B., Zhang, X.D. and Perry, M.J. (2020) Light Scattering by Pure Seawater at Subzero Temperatures. Deep-Sea Research Part I, 162, Article ID: 103306. https://doi.org/10.1016/j.dsr.2020.103306
[9]
Zhang, X.D., Hu, L.B. and He, M.X. (2009) Scattering by Pure Seawater: Effect of Salinity. Optics Express, 17, 5698-5710. https://doi.org/10.1364/OE.17.005698
[10]
Hu, L.B., Zhang, X.D. and Perry, M.J. (2019) Light Scattering by Pure Seawater: Effect of Pressure. Deep-Sea Research Part I, 146, 103-109. https://doi.org/10.1016/j.dsr.2019.03.009
[11]
Haltrin, V.I. (1999) Chlorophyll-Based Model of Seawater Optical Properties. Applied Optics, 38, 6826-6832. https://doi.org/10.1364/AO.38.006826
[12]
Arnon, S. and Kedar, D. (2009) Non-Line-of-Sight Underwater Optical Wireless Communication Network. Journal of the Optical Society of America A, 26, 530-539. https://doi.org/10.1364/JOSAA.26.000530
[13]
Jagadeesh, V.K., Choudhary, A., Bui, F.M. and Muthuchidambaranathan, P. (2014) Characterization of Channel Impulse Responses for NLOS Underwater Wireless Optical Communications. 2014 Fourth International Conference on Advances in Computing and Communications, Cochin, 27-29 August 2014, 77-79. https://doi.org/10.1109/ICACC.2014.24
[14]
Liu, W.H., Zou, D.F., Xu, Z.Y. and Yu, J.C. (2015) Non-Line-of-Sight Scattering Channel Modeling for Underwater Optical Wireless Communication. 2015 IEEE International Conference on Cyber Technology in Automation, Control, and Intelligent Systems, Shenyang, 8-12 June 2015, 1265-1268. https://doi.org/10.1109/CYBER.2015.7288125
[15]
Sait, M., Sun, X.B., Alkhazragi, O., Alfaraj, N., Kong, M.W., Ng, T.K. and Ooi, B.S. (2019) The Effect of Turbulence on NLOS Underwater Wireless Optical Communication Channels. Chinese Optics Letters, 17, Article ID: 100013. https://doi.org/10.3788/COL201917.100013
[16]
Priyalakshmi, B. and Mahalakshmi, K. (2020) Channel Estimation and Error Correction for UWOC System with Vertical Non-Line-of-Sight Channel. Wireless Networks, 26, 4985-4997. https://doi.org/10.1007/s11276-020-02376-2
[17]
Sait, M., Guo, Y.J., Alkhazragi, O., Kong, M.W., Ng, T.K. and Ooi, B.S. (2021) The Impact of Vertical Salinity Gradient on Non-Line-of-Sight Underwater Optical Wireless Communication. IEEE Photonics Journal, 13, Article ID: 7300609. https://doi.org/10.1109/JPHOT.2021.3121169
[18]
Prieur, L. and Sathyendranath, S. (1981) An Optical Classification of Coastal and Oceanic Waters Based on the Specific Spectral Absorption Curves of Phytoplankton Pigments, Dissolved Organic Matter, and Other Particulate Materials. Limnology and Oceanography, 26, 671-689. https://doi.org/10.4319/lo.1981.26.4.0671
[19]
Feistel, R. (2003) A New Extended Gibbs Thermodynamic Potential of Seawater. Progress in Oceanography, 58, 43-114. https://doi.org/10.1016/S0079-6611(03)00088-0
[20]
Feistel, R. (2008) A Gibbs Function for Seawater Thermodynamics for -6 to 80 °C and Salinity Up to 120g kg-1. Deep Sea Research Part I: Oceanographic Research Papers, 55, 1639-1671. https://doi.org/10.1016/j.dsr.2008.07.004
[21]
Ji, T.Y., Jiang, G.R., Shi, J., Zhou, Z.G. and Deng, B. (2015) Conversion Methods of Depth and Pressure in the Ocean. Marine Forecasts, 32, 45-50.
[22]
Poulin, C., Zhang, X.D., Yang, P. and Huot, Y. (2018) Diel Variations of the Attenuation, Backscattering and Absorption Coefficients of Four Phytoplankton Species and Comparison with Spherical, Coated Spherical and Hexahedral Particle Optical Models. Journal of Quantitative Spectroscopy & Radiative Transfer, 217, 288-304. https://doi.org/10.1016/j.jqsrt.2018.05.035
[23]
Shifrin, K.S. (1988) Physical Optics of Ocean Water. American Institute of Physics, New York.
[24]
Gabriel, C., Khalighi, M.A., Bourennane, S. Leon, P. and Rigaud, V. (2013) Monte-Carlo-Based Channel Characterization for Underwater Optical Communication Systems. IEEE/OSA Journal of Optical Communications & Networking, 5, 1-12. https://doi.org/10.1364/JOCN.5.000001
[25]
Mobley, C.D., Sundman, L.K. and Boss, E. (2002) Phase Function Effects on Oceanic Light Fields. Applied Optics, 41, 1035-1050. https://doi.org/10.1364/AO.41.001035
Wu, T.F., Ma, J.S., Su, P., Yuan, R.Z. and Cheng, J.L. (2019) Modeling of Short-Range Ultraviolet Communication Channel Based on Spherical Coordinate System. IEEE Communications Letters, 23, 242-245. https://doi.org/10.1109/LCOMM.2018.2890518
[28]
Xu, F., Khalighi, M.A. and Bourennane, S. (2011) Impact of Different Noise Sources on the Performance of PIN- and APD-Based FSO Receivers. 11th International Conference on Telecommunications, Graz, 15-17 June 2011, 211-218.
