Underwater speech communications with a modulated laser

In this paper, texts were experimentally transmitted by pulse width modulation (PWM) using an underwater wireless optical communication system (UWOC) in a channel containing water of varying salinity as a result of changes in the concentration of sodium chloride (NaCl). Mathematical equations are used using a MATLAB program to compare theoretical and practical results at different slop angle (θ0). (NaCl) concentration was changed from (0% w/v) to (90% w/v) to achieve different salinity of water (i.e., from clear water to turbid water). A diode laser with a power of 30 mW and a wavelength of 532 nm has been employed in the transmitter. The experimental results show that the extinction coefﬁcient or the overall attenuation C(λ) is equal to (0.083/m) in the water containing a low concentration of (NaCl) which is consistent with pure seawater. Additionally, the obtained optical power (PR) and the signal to noise ratio (S/N) decreases to (27.6) mW and (23.99) dB, respectively. Furthermore, it was found that the water had a maximum total attenuation C(λ) equal to (2.565/m) in the water containing a high concentration of (NaCl) which was compatible with turbid harbour water, as well as the received power and (S/N) decreases to (2.306) mW and (13.2) dB, respectively. The theoretical results were similar to the practical results when the slope angle of the target or detector relative to the optical transmitter was (zero).

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“…The propagation loss factor as a function of wavelength and channel length according to Berr-lambert law is [3,42].…”

Section: Optical Signal Fading Due To Salinity Of Uwoc Channelmentioning

confidence: 99%

Experimental Study of Underwater Wireless Optical Communication from Clean Water to Turbid Harbor under Various Conditions

Adnan¹,

Hassan²,

Alchalaby³

et al. 2021

IJDNE

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“…Underwater laser communication (1)(2)(3)(4)(5)(6), underwater laser imaging (7)(8)(9)(10) and deep-sea exploration (11)(12)(13)(14)(15) and precision underwater positioning systems (16) have attracted much attention, along with the development of blue and green laser technology. Seawater is a very complex multicomponent aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Optical Properties of Sodium Copper Chlorophyllin in Aqueous Solution

Peng

Han

et al. 2017

Journal of Applied Biomaterials & Functional Materials

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Background: Sodium copper chlorophyllin (SCC), as one of the derivatives of chlorophyll -with its inherent green features; good stability for heat, light, acids and alkalies; unique antimicrobial capability; and particular deodorization performance -is widely applied in some fields such as the food industry, medicine and health care, daily cosmetic industry etc. SCC, as one of the metal porphyrins, has attracted much attention because of its unique electronic band structure and photon conversion performance. To promote the application of SCC in materials science; energy research and photonics, such as fast optical communications; and its use in nonlinear optical materials, solar photovoltaic cells, all-optical switches, optical limiters and saturable absorbers, great efforts should be dedicated to studying its nonlinear optical (NLO) properties. Methods: In this study, the absorption spectra and NLO properties of SCC in aqueous solution at different concentrations were measured. The Z-scan technique was used to determine NLO properties. Results:The results indicated that the absorption spectra of SCC exhibit 2 characteristic absorption peaks located at the wavelengths 405 and 630 nm, and the values of the peaks increase with increasing SCC concentration. The results also showed that SCC exhibits reverse saturation absorption and negative nonlinear refraction (selfdefocusing). Conclusions: It can be seen that SCC has good optical nonlinearity which will be convenient for applications in materials science, energy research and photonics.

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“…Coherent and powerful continuous wave (CW) lasers in the visible are widely needed for various applications such as laser cooling, medicine diagnostics, underwater optical communications, high resolution spectroscopy, etc. [1][2][3][4][5]. On the other hand, IR lasers are currently proposed for many space applications such as gravitational wave detection, inter-satellites or ground to space optical communications, earth observations, etc.…”

Section: Introductionmentioning

confidence: 99%

Frequency tripled 1.5 µm telecom laser diode stabilized to iodine hyperfine line in the 10−15 range

Philippe

Targat

Holleville

et al. 2016

2016 European Frequency and Time Forum (EFTF)

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We report on telecom laser frequency stabilization to narrow iodine hyperfine line in the green range of the optical domain, after a frequency tripling process using two nonlinear PPLN crystals. We have generated up to 300 mW optical power in the green (P3ω), from 800 mW of infrared power (Pω.). This result corresponds to an optical conversion efficiency η = P3ω/Pω ~ 36 %. To our knowledge, this is the best value ever demonstrated for a CW frequency tripling process. We have used a narrow linewidth iodine hyperfine line (component a1 of the 127 I2 R 35 (44-0) line) to stabilize the IR laser yielding to frequency stability of 4.8x10 -14 τ -1/2 with a minimum of 6x10 -15 reached after 50 s of integration time. The whole optical setup is very compact and mostly optically fibered. This approach opens the way for efficient and elegant architecture development for space applications as one of several potential uses.

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Underwater speech communications with a modulated laser

Cited by 15 publications

References 9 publications

Experimental Study of Underwater Wireless Optical Communication from Clean Water to Turbid Harbor under Various Conditions

Experimental Study of Underwater Wireless Optical Communication from Clean Water to Turbid Harbor under Various Conditions

Nonlinear Optical Properties of Sodium Copper Chlorophyllin in Aqueous Solution

Frequency tripled 1.5 µm telecom laser diode stabilized to iodine hyperfine line in the 10−15 range

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